Glossary
The field's terms, acronyms, expressions, jargon, and lore - defined, sourced, and linked to the tools that compute them.
1242 terms
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- "a VPN makes you anonymous"loreDisputed / commonly mistoldA commercial VPN moves your trust from the local network to the VPN company: it hides traffic from the coffee shop and your IP from sites, while seeing everything itself.
- a patchy serverloreDisputed / commonly mistoldThe oldest explanation of how Apache got its name: it was a server made of patches.
- AAAAacronymThe DNS record that maps a hostname to an IPv6 address.
- abandonwarejargonSoftware whose vendor is gone or has walked away: no patches, no support, no legal way to buy it - and often no way to run it safely.
- ABNT (Associação Brasileira de Normas Técnicas)acronymThe Brazilian Association of Technical Standards: Brazil's national standards body and its ISO member.
- ACIDacronymThe four guarantees a reliable database transaction should provide.
- ACLacronymAccess Control List: an ordered set of permit and deny rules evaluated top-down against traffic, with an implicit deny waiting at the end.
- ACMEacronymA protocol that automates getting and renewing TLS certificates.
- ACSacronymThe endpoint where a SAML response is delivered to the application.
- Active DirectorytermMicrosoft's directory service: the domain's phone book and security authority - users, groups, machines, and the permissions binding them.
- active-active vs. active-passiveexpressionThe two shapes of high availability: both nodes serving traffic, or one serving while the other waits.
- ADacronymMicrosoft's directory service for identity and authentication.
- Ada LovelaceloreThe 19th-century mathematician often called the first programmer for her notes on Babbage's Analytical Engine.
- ADCacronymA device that load-balances and optimizes application traffic.
- administrative distancetermThe trust ranking a router applies when two routing sources offer the same prefix: lower wins, so connected beats static beats OSPF beats BGP-learned.
- ADSLacronymAsymmetric Digital Subscriber Line: broadband over the existing telephone pair by frequency division - voice below ~4 kHz, data above, a DSLAM terminating the data side at the exchange. Asymmetric because downstream gets most of the spectrum. Its arrival made home connections always-on.
- ADSPacronymF5's unified platform branding for application delivery and security.
- AEADacronymA cipher that encrypts and authenticates in one step, so tampering fails as a single operation.
- aerial vs. underground plantexpressionThe two ways outside plant reaches customers: on poles (cheap, fast, storm-exposed) or buried (costly, slow, backhoe-exposed).
- AESacronymThe standard symmetric block cipher used almost everywhere for bulk encryption.
- AgiletermThe 2001 Manifesto and everything it unleashed - individuals over processes, working software over documentation, responding to change over following the plan.
- air gaptermIsolating a system by giving it no network connection at all: the security control made of literal absence.
- AJAXacronymA technique for updating a web page without a full reload.
- alarm stormjargonOne real failure detonating into thousands of secondary alarms across the monitoring system.
- alert fatiguejargonThe numbness that sets in when monitoring pages so often that real alerts drown among the false ones.
- all models are wrongexpressionGeorge Box's statistics proverb: every model simplifies falsely - the question is whether it is useful anyway.
- all your base are belong to usloreA garbled line from a badly translated 1991 video game that became one of the first viral internet memes.
- ALOHAnetloreThe 1971 University of Hawaii radio network whose random-access scheme became the ancestor of Ethernet's collision handling.
- ALPACAloreA 2021 cross-protocol attack that confuses TLS services sharing a certificate.
- ALPNacronymThe TLS handshake field that negotiates which application protocol to use.
- AltaVistaloreThe search engine that led the web before Google, built at DEC as a way to stress-test a processor.
- amateur radiotermA licensed radio service for self-training, experimentation, and non-commercial communication, with allocations across the whole spectrum.
- Amdahl's lawexpressionThe speedup from parallelizing a task is capped by its serial fraction: infinite processors cannot beat 1/s.
- analog vs digitaltermThe distinction between a continuous signal that varies smoothly and a discrete one built from countable steps, and the boundary the whole digital age is spent crossing.
- ANATELloreAgência Nacional de Telecomunicações: Brazil's telecom regulator, created by the Lei Geral de Telecomunicações (Law 9.472, July 1997) to set rules and supervise the privatized sector in the public interest.
- anonymizationtermTransforming data so individuals can no longer be identified by any reasonably available means - the exit door from data protection law.
- ANPDacronymAutôridade Nacional de Proteção de Dados: Brazil's data protection authority - regulator, enforcer, and interpreter of the LGPD.
- anycasttermOne IP address announced from many locations, so users reach the nearest instance.
- Apache HTTP Server (httpd)termThe web server that ran most of the internet for the best part of two decades, begun in 1995 as coordinated patches to a server nobody was maintaining.
- Apache Software Foundation (ASF)acronymThe non-profit incorporated in June 1999 so the Apache projects would outlive any individual volunteer.
- APIsec UniversitytermFree, certificate-granting API-security training - the fastest on-ramp into the OWASP API Top 10 world.
- App ConnectortermZPA's lightweight VM/container beside a private application, making only outbound TLS connections to Service Edges - enrolled with a provisioning key, discovering apps via its own DNS vantage.
- App profile (ZCC)termThe Zscaler Client Connector policy object that decides per-application handling on the device: which destinations bypass the tunnel via its PAC logic, and platform-specific behavior per operating system.
- AppleTalkloreApple's plug-and-play networking suite of the 1980s and 90s - zero-configuration before the term existed, now discontinued.
- Application segmenttermZPA's unit of application definition: a set of FQDNs, wildcards, or IP addresses plus their ports, naming what can be reached. Access policy matches top-down against the most specific segment.
- archive formats (zip, tar, gz, 7z, rar, iso, cab)termContainer formats that bundle files together, compress them, or both - and the distinction between those two jobs is the thing most people never learn.
- Ariane 5 Flight 501loreThe 1996 maiden launch destroyed by an integer overflow in software reused from Ariane 4.
- ARPacronymAddress Resolution Protocol: how a host asks 'who has this IP?' on the local network and learns the answering MAC address.
- ARPANETtermThe packet-switched network funded by ARPA that grew into the internet, beginning with four university nodes in 1969.
- AS (autonomous system)acronymA network under one administrative routing policy, identified by an ASN.
- AS3acronymAn F5 extension for declaratively configuring application services via JSON.
- ASICacronymApplication-Specific Integrated Circuit: a chip built to do one job, fast, and incapable of being repurposed.
- ASLRacronymRandomizing where a process's memory regions land, so their addresses differ on every run.
- ASNacronymA number identifying a network under one routing policy.
- assume breachexpressionThe security posture that plans as if attackers are already inside, because someday they will be.
- asymmetric routingtermTraffic out one path and back another: perfectly legal IP behavior that quietly breaks stateful firewalls expecting to see both directions.
- ATMacronymAsynchronous Transfer Mode - the 1990s bet that all traffic, voice to data, should ride fixed 53-byte cells with hard QoS. Ethernet and IP won instead.
- attack surfacetermEverything an attacker can reach and try: exposed services, APIs, credentials, people - the sum of ways in.
- attack vectortermThe specific path or means by which an attacker reaches and compromises a target.
- attackers only need to be right onceexpressionThe defender's dilemma: attackers can fail repeatedly at no cost, while defense must hold everywhere, always.
- attenuationtermSignal loss over distance and through obstacles, measured in dB - the budget every link spends whether copper, fiber, or radio.
- Atwood's lawexpression'Any application that can be written in JavaScript, will eventually be written in JavaScript.'
- audit trailtermThe tamper-evident record of who did what, when, and from where - the API log every investigation starts from.
- authentication adaptertermThe PingFederate component that actually authenticates a user - or receives one authenticated elsewhere: HTML Form, HTTP Basic, Kerberos, OpenToken, and Reference ID each embody a different integration pattern.
- Authentication Policy ContracttermThe normalized attribute set an authentication policy fulfills on every successful path: whatever adapter or IdP connection authenticated the user, downstream configuration consumes the same contract.
- authentication policy treetermPingFederate's runtime decision tree for authentication: nodes are authentication sources and selectors, Fail and Success branches express fallbacks, reusable fragments capture common sequences, and every successful path ends by fulfilling a policy contract.
- autoscalingtermCapacity that follows demand: instances added on load, removed in quiet - elasticity as the cloud's founding promise.
- availability zonetermOne or more data centers with independent power, cooling, and network inside a region - close enough for sync replication, far enough to fail separately.
- AWSacronymAmazon's cloud platform - compute, storage, networking, and hundreds of services.
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- Babel FishloreThe web's first machine-translation service, shipped by AltaVista.
- baby giantjargonA frame just slightly over the classic 1518-byte Ethernet maximum - grown by tags and labels, not by payload.
- backhaultermThe links carrying aggregated access traffic from towers, cabinets, and OLTs back to the network core - the middle mile.
- backhoe fadejargonTelecom's dry name for total signal loss caused by construction equipment digging through the fiber.
- backup vs. snapshotexpressionSnapshots are fast local restore points sharing the original's fate; backups live elsewhere and survive it - only the second answers ransomware.
- BADoSacronymA defense that detects denial-of-service by learning normal traffic behavior.
- bastion hosttermThe one hardened, audited entry point for administrative access to a private network - a jump host by design rather than accident.
- bazloreThe third metasyntactic placeholder, following foo and bar.
- beaconingjargonThe regular, automated check-ins a compromised host makes to its command server.
- BEASTloreA 2011 attack decrypting TLS 1.0 traffic by exploiting predictable CBC initialization vectors.
- BEBacronymAn edge device in an Ethernet fabric that encapsulates traffic into the backbone.
- belt and suspendersexpressionWearing two independent safeguards for the same failure - if one lets go, the trousers stay up.
- BFDacronymBidirectional Forwarding Detection - a tiny, protocol-agnostic hello stream that detects a dead path in milliseconds, so routing protocols can fail over before users notice.
- BGPacronymThe protocol that decides how traffic is routed between the large networks that make up the internet.
- BHackloreThe technical security conference of Belo Horizonte, and one of the events that made the Brazilian scene something other than a Sao Paulo scene.
- big ball of mudexpressionA system with no discernible architecture - haphazardly structured, sprawling, and held together by expedience.
- bikesheddingloreSpending disproportionate discussion on a trivial detail while an important, complex decision passes with little scrutiny.
- BINDacronymThe most widely deployed DNS server software.
- biometric datatermMeasurements of the body used to identify the person - fingerprints, face geometry, voice, gait - identifiers you cannot rotate after a breach.
- bisectiontermHalving a search space repeatedly until one candidate remains, so that a thousand possibilities take ten tests rather than a thousand.
- bitloreThe smallest unit of information, a single choice between 0 and 1, and the atom on which the entire digital world is built.
- bit bangingjargonDriving a hardware protocol entirely in software, toggling a pin bit by bit instead of using a dedicated controller.
- bit bucketjargonThe imaginary place discarded data goes - the destination of everything sent to /dev/null.
- bit rotexpressionThe way working software seems to decay over time as the world around it changes.
- Black HattermThe corporate-facing security conference: research Briefings and paid Trainings, run days before DEF CON.
- blast radiusjargonHow far the damage spreads when one component fails or is compromised.
- bloatwarejargonUnwanted software that arrives pre-installed - trials, toolbars, vendor utilities - consuming resources nobody offered.
- block ciphertermA cipher that encrypts fixed-size blocks (AES: 128 bits), relying on a mode of operation to handle real message lengths.
- blue boxloreThe phone-phreaking device that generated the 2600 Hz tone and signaling frequencies to seize control of the long-distance network.
- blue screen of deathjargonWindows's full-screen fatal-error display, and by extension any total, user-visible system failure.
- blue teamtermThe defenders: the people and tooling that detect, respond to, and recover from attacks.
- BlueKeeploreA 2019 wormable flaw in Microsoft Remote Desktop Services.
- bogonjargonA packet claiming a source address that could never legitimately appear on the public internet.
- bohrbugloreA solid, reproducible bug that behaves the same way every time you run it.
- boil the oceanexpressionTo attempt something so broad or ambitious that it is doomed by its own scope.
- borkedjargonBroken, in the resigned voice of someone who has to fix it - as in 'the upgrade borked the standby unit'.
- botnettermA network of compromised machines controlled as one, often for attacks or spam.
- braindumpjargonA verbatim collection of leaked real exam questions, sold or shared so candidates can memorize their way to a certification.
- BREACHloreA 2013 variant of CRIME that targets HTTP response compression instead of TLS.
- break-glass accountexpressionThe sealed emergency credential that bypasses normal controls when identity itself is down - stored offline, alarmed on use, tested on schedule.
- brickedjargonRendered as functional as a brick - a device so broken it will not even boot.
- broadcasttermOne-to-all delivery inside a network segment: a frame or packet addressed so that every host must receive and process it.
- broadcast stormtermThe meltdown where broadcast frames multiply through a switching loop until the network drowns in its own traffic.
- Brooks's lawexpressionThe principle that adding people to a late software project makes it later.
- brownoutjargonA service that is up but deliberately or visibly degraded - dimmed, like the power-grid original, rather than dark.
- browser fingerprintingtermIdentifying a browser by its combination of traits - fonts, canvas rendering, hardware, settings - unique enough to track without any cookie.
- brute forcetermTrying every possibility until one works.
- BSDacronymA Unix lineage; also the name of the original syslog format.
- BSides São PauloloreThe community-run, free security conference of Sao Paulo - born inside Garoa Hacker Clube in 2011, now among the largest BSides anywhere.
- buffer overflowtermWriting more data into a buffer than it can hold, so the excess lands in adjacent memory that was never meant to receive it.
- bufferbloatjargonLatency caused by oversized buffers: routers queue so much that packets arrive very late instead of being usefully dropped.
- bug (the first computer bug)loreDisputed / commonly mistoldThe 1947 logbook entry in which a moth trapped in a Harvard Mark II relay was taped down beside the note "First actual case of bug being found."
- bug bountytermA program that pays researchers for responsibly reporting security flaws.
- BUMacronymSwitching shorthand for the three traffic types a switch cannot deliver to a single known port and therefore floods: broadcast, unknown unicast, and multicast.
- burn ratejargonHow fast a finite budget is being consumed - cash in a startup, error budget in SRE practice.
- bus factorexpressionThe number of people who would have to be hit by a bus before a project stalls for lack of knowledge.
- bus topologytermA single shared cable that every station taps into, with terminators at each end.
- BYODacronymBring Your Own Device: employees working from personal hardware - cheaper fleets, happier users, and a security perimeter made of other people's phones.
- BYOIPacronymBring Your Own IP: advertising your own address blocks from the cloud provider's network - your reputation and whitelistings, their infrastructure.
- byteloreA group of bits handled as a unit, standardized to eight, and the everyday quantum of computer storage.
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- C10K problemjargonThe problem, named in 1999, of handling ten thousand simultaneous connections on one machine.
- C2acronymThe infrastructure an attacker uses to control compromised machines remotely.
- C3DacronymAn F5 feature that re-signs client certificates for backend mutual TLS.
- C5acronymGermany's government-backed cloud-security attestation, defined by the BSI.
- CAacronymThe trusted issuer that signs digital certificates.
- CAAacronymA DNS record declaring which certificate authorities may issue for a domain.
- Cable categories (Cat 5e-8)termThe TIA-568 performance grades of twisted-pair cable - what 'Cat 6A' actually promises.
- callsigntermA unique identifier issued to a licensed radio station, structured as prefix, digit, and suffix.
- Campus PartyloreThe tent-city technology festival: thousands of campistas pitching tents inside a convention pavilion for a week of talks, hackathons, and 24/7 connectivity.
- canary in the coal mineexpressionA sacrificial early-warning signal: something small that suffers first, so the rest can react in time.
- canary tokentermA booby-trapped credential, file, or link that phones home when touched - fake AWS keys that alarm the moment someone tries them.
- Captain Crunch (the 2600 Hz whistle)loreThe phone-phreaking legend that a toy whistle emitting 2600 Hz could seize AT&T long-distance trunks.
- Captain MidnightloreThe 1986 HBO satellite hijacking by a Florida uplink engineer protesting a $12.95 monthly fee.
- CAPTCHAacronymA challenge meant to tell humans and bots apart.
- cargo cult programmingloreCopying code or rituals that seem to work without understanding why, in the hope the result follows.
- CarriertermAn operator that moves somebody else's traffic: the physical substrate everything above it assumes.
- carrier hoteljargonA building whose tenants are networks: dozens of carriers and providers colocated where fiber routes converge.
- CarterfonetermThe 1968 FCC decision that let equipment the telephone company had not made be attached to the telephone network.
- CASBacronymCloud Access Security Broker: the control point between users and SaaS - visibility into which cloud apps are used and policy over what flows into them.
- castle-and-moatexpressionThe perimeter security model: strong walls at the edge, broad trust for anyone already inside.
- cattle, not petsexpressionThe mindset that servers should be disposable and interchangeable, not lovingly maintained individuals.
- CBCacronymAn older block-cipher mode that chains blocks together but provides no integrity on its own.
- CCIacronymCloud Confidence Index - Netskope's 0-100 risk rating for tens of thousands of cloud applications, scored against objective criteria adapted from the Cloud Security Alliance's guidance and grouped into enterprise-readiness categories such as certifications and compliance, data protection, access control, auditability, disaster recovery, and legal/privacy terms.
- CCMacronymAn AEAD mode combining counter-mode encryption with a CBC-based authentication tag.
- CCPA / CPRAacronymCalifornia's consumer privacy law: rights to know, delete, and opt out of the sale of personal information - amended and hardened by the CPRA.
- CDATAacronymAn XML section whose content is not parsed as markup.
- CDCiber (Centro de Defesa Cibernética)acronymBrazil's military cyber defence centre, created in 2010 under the Ministry of Defence and later expanded into a full command.
- CDNacronymContent Delivery Network: copies of your content cached at edge locations worldwide, so users fetch from nearby instead of from origin.
- CE (Customer Edge)acronymA node that connects a customer site into F5 Distributed Cloud.
- CERT (team)acronymA team that coordinates response to security incidents.
- CGI.brloreComitê Gestor da Internet no Brasil: the multistakeholder Internet Steering Committee created in 1995 by the Science & Technology and Communications ministries to set internet directives and policies in Brazil, including governance of the .br domain.
- CGNATacronymCarrier-Grade NAT: the ISP shares one public IPv4 address among many subscribers, translating at provider scale because the addresses ran out.
- chain analysistermTracing cryptocurrency flows across a public blockchain to follow the money.
- change management (ITSM)termThe gate through which production changes pass: assessed for risk, scheduled in windows, approved, and rollback-ready.
- Chaos Computer ClubloreEurope's oldest and most influential hacker association - German, political, and deeply serious about technology and civil rights.
- Chaos MonkeyjargonNetflix's tool that randomly kills production instances, and the name for deliberately injecting failure to prove resilience.
- CHAPacronymThe Challenge-Handshake Authentication Protocol - PPP's secure alternative to sending a password in the clear.
- check layer 1expressionThe first commandment of troubleshooting: before anything clever, confirm the cable, the port, the power.
- Chesterton's fenceexpressionThe principle that you should not remove something until you understand why it was put there.
- choose boring technologyexpressionDan McKinley's principle: prefer proven, well-understood tools, and spend your few innovation tokens deliberately.
- CIA triadtermThe three core goals of information security: confidentiality, integrity, and availability.
- CIDRacronymA compact way to write an IP network as an address plus a prefix length, like 10.0.0.0/8.
- cipher suitetermThe specific set of algorithms a TLS connection agrees to use for key exchange, encryption, and integrity.
- circuit breakertermA pattern that stops calling a failing dependency for a while, so one outage does not drag everything down.
- Cisco certifications (CCNA / CCNP / CCIE)termThe certification ladder that defined the industry: CCNA to prove you can run a network, CCNP to prove you can build one, CCIE to prove it under lab pressure.
- Cisco LivetermThe vendor mega-event that began as Networkers: certification labs, the World of Solutions floor, and the annual pilgrimage of the Cisco-certified.
- CISSPacronymThe management-level security certification - (ISC)2's flagship since 1994: eight domains, a mile wide, and the credential security leadership job posts ask for by name.
- Citizens Band (CB)termA small licence-free or lightly-licensed radio allocation near 27 MHz with fixed channels and low power limits.
- Clarke's third lawexpression'Any sufficiently advanced technology is indistinguishable from magic.'
- clean pipejargonInternet transit that arrives already scrubbed of DDoS traffic - the provider filters the flood upstream and delivers only the clean flow.
- CLIacronymA text-based interface where you type commands to control software.
- client-servertermAn architecture where requesting clients talk to a designated server that holds the resource and answers.
- ClippyloreMicrosoft's animated paperclip assistant, beloved in memory and despised in use, the cautionary tale of proactive UI.
- Cloud Security AlliancetermThe industry body that defines how cloud security is assessed and attested.
- cloud VPNtermThe managed IPsec tunnel between your premises and your VPC - the quick, encrypted, internet-riding alternative to a dedicated circuit.
- CMDBacronymConfiguration Management Database: the inventory of every asset and the relationships between them - what talks to what, and who screams when it dies.
- CMTSacronymCable Modem Termination System: the head-end router that owns every cable modem in its footprint, granting each its timeslots and speed tier.
- CNAMEacronymA DNS record that makes one name an alias for another.
- CNAPPacronymCloud-Native Application Protection Platform: the industry's umbrella merging posture, workload protection, and permissions analysis into one platform.
- COBITacronymISACA's governance framework for enterprise IT - the auditor's answer to the question ITIL doesn't ask: who decides, who is accountable, and how do we prove it.
- Code RedloreThe July 2001 IIS worm that defaced sites with 'Hacked By Chinese!' and infected hundreds of thousands of servers in hours.
- code smellexpressionA surface sign in code that hints at a deeper design problem, without being a bug itself.
- cold-potato vs. hot-potato routingexpressionTwo philosophies for carrying traffic: hot-potato hands it to the next network as soon as possible; cold-potato keeps it on your backbone as long as possible.
- collision domaintermThe stretch of shared network in which two devices transmitting at once garble each other: one collision domain, one conversation at a time.
- compliance is not securityexpressionThe audit-season reminder that passing a checklist proves documentation, not protection.
- Computer InquirytermThe FCC proceedings that drew a line between regulated communications and unregulated data processing.
- conditional accesstermSign-in policy with context: who, from which device, from where, at what risk level - and only then, with which second factor, access.
- ConfickerloreThe 2008 Windows worm that built one of history's largest botnets and popularized domain-generation algorithms.
- configuration driftjargonThe slow divergence between what a system is supposed to look like and what it actually runs.
- confused deputytermA privileged service tricked into using its authority on behalf of an unauthorized caller - the deputy is honest, just confused about who is asking.
- consent (privacy)termOne lawful basis among several: a freely given, specific, informed, unambiguous yes - revocable as easily as it was given.
- containmenttermLimiting how much a fault affects, without addressing why it happened.
- Content Security PolicyacronymA browser policy that restricts what a page may load and run, to blunt attacks like XSS.
- control planetermThe part of a system that makes decisions, as opposed to the data plane that moves the traffic.
- Conway's lawexpressionThe observation that systems end up mirroring the communication structure of the organizations that build them.
- cookie bannertermThe consent interface for non-essential tracking - born of the ePrivacy rules and GDPR consent standards, degraded by design into a click-through ritual.
- CORSacronymThe browser mechanism that decides whether a web page may make requests to a different origin.
- CORS preflighttermThe OPTIONS request a browser sends first, asking the server's permission, before it is willing to send certain cross-origin requests at all.
- CortextermPalo Alto Networks' security-operations family, announced in February 2019: detection, response, and automation for the SOC.
- COSacronymCorporation for Open Systems: a vendor consortium formed to certify OSI conformance.
- cowboy codingjargonDevelopment with no process between the idea and production: no review, no tests, no branch, just push.
- CPEacronymCustomer Premises Equipment: any provider-managed device at the customer site - modem, ONT, router - the equipment half of every 'is it you or is it me?' call.
- crash cartjargonThe wheeled cart with a monitor, keyboard, and cables that gets pushed to a server that stopped answering the network.
- credential stuffingtermAutomated login attempts using username and password pairs stolen from other breaches.
- CRIMEloreA 2012 attack recovering secrets by observing the size of compressed TLS requests.
- CRLacronymA published list of certificates that have been revoked.
- cross-border data transfertermMoving personal data between jurisdictions - lawful only through recognized mechanisms: adequacy decisions, contractual clauses, or specific exceptions.
- Crossover cabletermA patch cord wired T568A on one end and T568B on the other - once required to connect like devices, now made obsolete by auto-MDIX.
- crown jewelsjargonThe small set of assets whose compromise would actually hurt: the data, keys, and systems the business cannot lose.
- CRUDacronymThe four basic operations of persistent storage: create, read, update, and delete.
- cruftjargonThe accumulated leftover junk in a system - old configs, dead code, objects nobody dares delete.
- crunchy outside, chewy centerexpressionThe classic critique of perimeter-only security: a hard shell around a soft, defenseless inside.
- CryptoRaveloreSão Paulo's crowdfunded cryptoactivism marathon: 24 uninterrupted hours of privacy, security, and digital-rights activities - free, volunteer-run, and pointedly without corporate sponsorship.
- CSA STARacronymThe Cloud Security Alliance's public registry of cloud-provider security postures - self-assessment through third-party certification.
- CSMA/CAacronymWi-Fi's channel etiquette: a radio cannot hear a collision while it is transmitting, so stations work to avoid collisions up front with waits, random backoff, and per-frame acknowledgements.
- CSMA/CDacronymClassic Ethernet's channel etiquette: listen before you talk, talk only when the wire is quiet, and if two stations collide anyway, stop, jam, and retry after a random backoff.
- CSPMacronymCloud Security Posture Management: continuous scanning of cloud configuration against best practice - the tool that finds the public bucket before the researcher does.
- CSRacronymA signed request containing the public key and details for a certificate.
- CSRFacronymAn attack that tricks a logged-in user's browser into making an unwanted request.
- Cunningham's lawexpressionThe observation that the best way to get a right answer online is to post a wrong one.
- CVEacronymA public catalogue entry that uniquely identifies one specific known vulnerability.
- CVSSacronymA standard 0 to 10 score that rates the severity of a vulnerability.
- CWEacronymA community catalog of software weakness types, each with a stable identifier like CWE-787.
- CWNP / CWNAacronymThe vendor-neutral Wi-Fi certification body - and CWNA, its flagship: the credential that proves you understand radio, not just controllers.
- CWPPacronymCloud Workload Protection Platform: runtime defense for the workloads themselves - VMs, containers, functions - vulnerabilities, integrity, and behavior.
- Cyber EssentialstermThe UK government's baseline cyber-hygiene certification, run by the NCSC.
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- "deleting a file erases it"loreDisputed / commonly mistoldDelete removes the directory entry and marks the space reusable - the bytes remain until overwritten, which recovery tools exploit daily.
- DADacronymAn IPv6 check that a chosen address is not already in use.
- daemontermA long-running background process that waits quietly to do its job, named after a benevolent spirit, not a demon.
- dark fibertermInstalled but unlit fiber strands leased as raw glass: the customer brings the optics and owns the capacity ceiling.
- dark launchjargonShipping a feature to production silently, running it on real traffic before any user can see it.
- dark webtermThe subset of the deep web reachable only through anonymity networks, where sites hide their location as well as their content.
- darknettermAn overlay network that runs on the public internet but is reachable only with specific software, configuration, or authorization.
- DARPA (Defense Advanced Research Projects Agency)acronymThe United States defence research agency created in 1958, and the funder of the network that became the internet.
- data breach notificationtermThe legal duty to report a personal-data breach to the authority and, when risk is high, to the affected people - on a clock that starts at discovery.
- data brokertermA company whose product is other people: profiles assembled from purchases, apps, public records, and location trails, sold to whoever pays.
- Data center tierstermThe Uptime Institute's I-to-IV classification of data-center resilience - from basic capacity to fault tolerance.
- Data centre operatortermColocation, hosting and interconnection: the businesses that own the places where networks physically meet.
- data controllertermThe party that decides why and how personal data is processed - and therefore the one accountable for it.
- data minimizationtermCollecting and keeping only the personal data you actually need, for only as long as you need it.
- Data PBXtermA switch that connected terminals to computers the way a PBX connected telephones to lines.
- data portabilitytermThe right to take your data with you in a machine-readable format - and, where feasible, have it sent straight to the next provider.
- Data Privacy FrameworktermThe mechanism for lawfully transferring personal data from the EU/UK/Switzerland to certified US companies.
- data processing agreementtermThe contract binding a processor to the controller's instructions: security measures, sub-processors, breach duties, and deletion at the end.
- data processortermThe party processing personal data on a controller's documented instructions - the cloud provider, the SaaS, the payroll bureau.
- data residencytermRequirements that certain data physically remain within a jurisdiction's borders - law expressed as region selection.
- data retentiontermKeeping data only as long as its purpose requires, then deleting on schedule - the discipline that shrinks both risk and discovery scope.
- data storetermA reusable connection definition to an external identity source - an LDAP directory with failover hosts and a service bind, or a JDBC database with its driver and validation query - configured once and referenced by validators, attribute lookups, and provisioning.
- DCVacronymProving you control a domain before a certificate is issued.
- DCWF (DoD Cyber Workforce Framework)acronymThe United States Department of Defense's own catalogue of cyber work roles, aligned with but distinct from the NICE Framework.
- DDoSacronymAn attack that overwhelms a service with traffic from many sources at once.
- dead droptermA method of passing information without the parties ever meeting.
- debuggingtermThe systematic process of finding and fixing defects in software.
- DECnetloreDigital Equipment Corporation's networking suite - the protocol that ran the VAX era, evolving from proprietary roots toward OSI.
- dedicated interconnecttermA private physical circuit from your premises into the cloud provider's edge - predictable latency, real bandwidth, no public internet in the path.
- Deep BlueloreThe IBM machine that defeated world chess champion Garry Kasparov in May 1997, the first machine victory over a reigning champion in match play.
- deep webtermEverything on the web that search engines do not index, which is most of it.
- DEF CONloreThe world's largest hacker conference - Las Vegas every August since 1993 - and the cultural center of gravity of the scene.
- default routetermThe route of last resort - 0.0.0.0/0 - matching everything no more specific route claims; the packet's way out of the building.
- default-free zonejargonThe part of the internet whose routers carry the full routing table and no default route - nowhere to forward blindly.
- defense in depthtermLayering multiple independent controls so that if one fails, others still stand.
- DEFLATE, gzip and zlibtermThe compression algorithm inside ZIP, PNG, Git and most of the web; the file format that wraps it; and the library that implements both.
- demarcation pointtermThe contractual boundary where the provider's network ends and the customer's begins - and with it, whose problem the fault is.
- dependency helljargonThe state where software cannot be installed or upgraded because its dependencies' versions conflict.
- DERacronymA strict binary encoding for X.509 certificates and keys.
- device drivertermThe software that teaches the operating system to speak to a specific piece of hardware - and the first suspect when that hardware misbehaves.
- DevSecOpstermA culture and practice of building security into development and operations, not bolting it on.
- DFacronymAn F5 hardware designation for a dual-fan platform variant.
- DHacronymA method for two parties to agree on a shared secret.
- DHCPacronymDynamic Host Configuration Protocol: hands each joining device an IP address, mask, gateway, and DNS servers, leased for a limited time.
- DHCP option 82termThe relay information option: the access device stamps each DHCP request with the physical line it arrived on, giving the ISP per-port identity.
- DICTacronymA protocol for querying network dictionary servers.
- differential privacytermA mathematical guarantee: query answers barely change whether or not any one person is in the dataset - privacy as provable noise.
- digital signaturetermA cryptographic proof that a message came from a specific key holder and was not altered.
- DistributortermA company that sells to resellers rather than to the organisations that use the equipment - the middle tier of two-tier distribution.
- DKIMacronymAn email-authentication method that cryptographically signs messages.
- DLPacronymData Loss Prevention: recognizing sensitive data - card numbers, records, secrets - and stopping it from leaving through email, uploads, or clipboards.
- DMZacronymDemilitarized zone: the buffer network between the internet and the inside, where public-facing servers live under stricter watch.
- DNSacronymThe system that translates human-readable names like example.com into IP addresses.
- DNS filteringtermBlocking or rewriting DNS answers to stop clients reaching chosen domains.
- DNS over HTTPSacronymSending DNS lookups inside encrypted HTTPS so they cannot be read or tampered with in transit.
- DNSKEYacronymThe DNS record that publishes a zone's public signing key.
- DNSSECacronymExtensions that let DNS answers be cryptographically verified.
- Do Not TracktermThe browser header that politely asked sites not to track - and, lacking any legal force, was almost universally ignored.
- DOCSISacronymThe standard that turns cable-TV coax into broadband, sharing spectrum among a neighborhood of modems under one CMTS scheduler.
- DoD (United States Department of Defense)acronymThe United States Department of Defense.
- dogfoodingjargonUsing your own product internally, so its failures bite you before they bite customers.
- DoHacronymDNS queries sent inside HTTPS, indistinguishable from ordinary web traffic.
- don't roll your own cryptoexpressionThe first commandment of applied cryptography: use the vetted algorithms and libraries, never your homemade ones.
- DoTacronymDNS queries carried inside TLS on their own port, 853.
- DPDacronymDead Peer Detection - how an IPsec endpoint learns its IKE partner is gone: an on-demand are-you-there exchange, so dead tunnels get torn down and failover can happen.
- DPIAacronymData Protection Impact Assessment: the structured 'what could this do to people?' analysis required before high-risk processing begins.
- DPOacronymData Protection Officer: the designated guardian of a data protection program - advisor inside, contact point for regulators and data subjects outside.
- DragonJARloreColombia's leading hacker conference, grown out of the DragonJAR community - and deliberately delivered entirely in Spanish.
- drift detectiontermSpotting the gap between infrastructure as declared and infrastructure as it actually is - the console edit that code never knew about.
- drink the Kool-AidexpressionTo adopt a belief or technology with uncritical, group-driven enthusiasm.
- drinking from the firehoseexpressionAbsorbing information far faster than anyone could - the universal description of onboarding into a complex system.
- drop cabletermThe final cable from the pole, pedestal, or splitter box to the customer's building - the piece of plant most exposed to weather, trees, and trucks.
- DROWNloreA 2016 attack that breaks TLS by exploiting a server's support for obsolete SSLv2.
- DRYexpressionThe principle that every piece of knowledge should have a single, authoritative representation in a system.
- DSARacronymData Subject Access Request: a person exercising their right to see the data held about them - and the clock that starts when they ask.
- DSLAMacronymDSL Access Multiplexer: the exchange-side rack that terminates hundreds of copper DSL lines and hands their traffic to the backhaul.
- DTLSacronymTLS adapted to run over UDP instead of TCP.
- dual stacktermRunning IPv4 and IPv6 side by side on the same hosts and links - the standard transition strategy while both internets coexist.
- dumpster divingjargonRecovering sensitive information from the trash - printouts, sticky notes, unwiped drives.
- duplex mismatchtermOne end at full duplex, the other at half: the link works, slowly and with late collisions - the classic 'network is weird' root cause of the 2000s.
- DVMRPacronymDistance Vector Multicast Routing Protocol - the first multicast routing protocol, and the engine of the MBone: RIP's logic, pointed at delivery trees.
- DWDMacronymDense Wavelength Division Multiplexing - many independent light colors down one fiber. The reason a single strand can carry terabits and the backbone of every long-haul network.
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- E1acronymThe international 2.048 Mb/s digital carrier - 32 timeslots of 64 kb/s, the E-carrier answer to T1, and the line Brazilian networking grew up on.
- east-west / north-south trafficexpressionThe two axes of data-center traffic: north-south crosses the perimeter to users; east-west flows between servers inside.
- ECDHacronymElliptic-curve key exchange - the non-ephemeral form lacks forward secrecy.
- ECDHEacronymA key-exchange method that gives every session its own throwaway keys, so past traffic stays safe if a long-term key leaks.
- ECDSAacronymA signature algorithm using elliptic curves - smaller keys than RSA for the same strength.
- ECMAacronymA standards body behind JavaScript and JSON specifications.
- ECMPacronymEqual-Cost Multi-Path: when several routes tie on cost, traffic is hashed across all of them - free load sharing, per flow, not per packet.
- ECSacronymAn EDNS option that forwards part of the client's address to the authoritative server.
- EDNSacronymAn extension that adds capabilities to the original DNS message format.
- EDRacronymEndpoint Detection and Response: the agent that records what endpoints do - processes, connections, changes - detects the malicious, and can isolate the host.
- EFFacronymThe nonprofit defending civil liberties in the digital world - and the maker of Certbot.
- EGPacronymExterior Gateway Protocol - the class of protocols that route BETWEEN autonomous systems, and also the name of the specific 1980s protocol BGP replaced.
- egress costtermThe per-gigabyte charge for data leaving the cloud - in is free, out is billed, and architecture quietly bends around that asymmetry.
- egress filteringtermControlling what may leave the network, not just what may enter - the outbound rules that starve malware of its command channel.
- EHFacronymAn out-of-band fix F5 issues for a specific urgent problem.
- EIA/TIAacronymThe standards lineage behind structured cabling - the TIA-568 family that defines the categories, connectors, and distances of every wiring closet.
- EIGRPacronymEnhanced Interior Gateway Routing Protocol - Cisco's advanced distance-vector protocol: the DUAL algorithm keeps loop-free backup routes precomputed, so convergence is nearly instant.
- EkopartyloreLatin America's biggest hacking conference: Buenos Aires, every year since 2001, where the region's security community - and more than a few world-class vulnerabilities - come out on stage.
- elastic IPtermA static public address you own and can remap between instances - identity that survives the workload behind it.
- elephant flowjargonA single long-lived flow so large it dominates a link - one elephant among thousands of mice.
- ELIZAloreJoseph Weizenbaum's 1966 chatbot whose users confided in a pattern-matching script, naming the ELIZA effect.
- EmacstermThe extensible editor from the GNU project, closer to a programmable environment that happens to edit text.
- Embedded systemtermA computer built into something that is not thought of as a computer, with a fixed job and usually nobody watching it.
- EMBRATELloreEmpresa Brasileira de Telecomunicações: Brazil's long-distance and data carrier, created in 1965 and folded into the Telebrás system; ran the country's first commercial internet trial in December 1994; privatized in 1998 to MCI WorldCom, sold to Telmex in 2004, incorporated into Claro in 2015.
- encryption is easy, key management is hardexpressionThe crypto veteran's summary: encrypting data is the easy part; protecting, rotating, and not losing the keys is the hard part.
- end-to-end encryptiontermEncryption where only the communicating endpoints can read the messages, not the servers in between.
- endianness (On Holy Wars)loreThe byte-ordering split whose names Danny Cohen borrowed from a satirical war in Gulliver's Travels.
- ENEacronymEnterprise Network Event: the 1988 trade show positioned as the OSI counterpart to the TCP/IP demonstrations.
- ENIacronymElastic Network Interface: the cloud's detachable virtual NIC - addresses, security groups, and MAC that can move between instances.
- entropytermA measure of unpredictability; in security, the randomness that makes keys and secrets hard to guess.
- envelope encryptiontermEncrypting data with a data key, then encrypting that key with a master key - bulk work done locally, the crown jewel guarded centrally.
- EOLacronymEnd of life: the date after which a product receives no fixes, no patches, and no vendor sympathy.
- ephemeral keytermA short-lived key generated for a single session and then discarded.
- EPSSacronymA data-driven score estimating the odds a vulnerability gets exploited.
- ES256acronymA JWT signing algorithm: ECDSA with SHA-256.
- escalationtermMoving a ticket up - functionally to deeper expertise, hierarchically to management - when the current tier cannot or should not resolve it.
- escalation (operational)termHanding a problem to someone with more authority, more knowledge, or the ownership needed to act on it.
- ESPacronymThe IPsec protocol that encrypts and authenticates packet payloads.
- EternalBlueloreThe NSA-developed SMB exploit leaked in 2017 that powered WannaCry and NotPetya.
- EthernettermThe LAN technology sketched at Xerox PARC in 1973 that won every networking war and now carries almost everything.
- EUIacronymAn IEEE identifier format used to build IPv6 interface IDs.
- event logtermThe operating system's diary of errors, warnings, and audits - where 'it just crashed' becomes a source, an ID, and a timestamp.
- everything fails, all the timeexpressionWerner Vogels' cloud axiom: at sufficient scale, failure is not an event but a permanent background condition.
- exit nodetermThe final Tor relay, where traffic leaves the network toward its destination.
- exit scamtermWhen an operator suddenly shuts down and disappears with users' funds.
- EXOSacronymExtreme Networks' switch operating system.
- exploittermCode or a technique that turns a vulnerability into actual unintended behaviour.
- eyeball networkjargonAn ISP whose customers are people watching screens - the networks where the eyeballs are.
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- "forced password changes make you safer"loreDisputed / commonly mistoldMandatory 90-day rotations trained people into Password1, Password2 - predictable mutations attackers model. Current guidance: long unique passphrases, changed on evidence of compromise.
- F5 DevCentraltermF5's official technical community - articles, Q&A, and two decades of iRules knowledge, with a recognized MVP program.
- FA (Fabric Attach)acronymA protocol that auto-attaches edge switches to an Ethernet fabric.
- fail open vs. fail closedexpressionThe design choice of what a control does when it breaks: allow everything through, or block everything.
- failovertermMoving service from a failed component to a standby, restoring availability without repairing the fault.
- FAPESPloreFundação de Amparo à Pesquisa do Estado de São Paulo: São Paulo's research-funding foundation whose data-processing team built Brazil's academic network (ANSP), received Jon Postel's delegation of the .br domain in 1989, made the country's first TCP/IP connection in 1991 (to ESnet via Fermilab), and ran .br registration until NIC.br took over.
- fat-fingerjargonTo cause an outage with a typo - the wrong command, the wrong device, or one digit off in a config line.
- FedRAMPacronymThe US government's standardized security-authorization program for cloud services - High, Moderate, and Low baselines.
- FenasoftloreBrazil's giant computing fair of the 1990s: the Anhembi pavilions, endless entry queues, and a nation meeting the personal computer - all at once.
- FIPSacronymUS government standards for cryptography and computer security.
- firefightingjargonOperating in permanent emergency mode: all effort goes to the incident of the day, none to preventing the next one.
- FirmwaretermSoftware that ships as part of a device and is expected to be there before anything else runs.
- Firmware vs softwareexpressionThe distinction a vendor draws between code that is part of the device and code that runs on top of it - and the reason it decides who fixes your problem.
- FIRST (org)acronymThe global body of incident-response teams behind CVSS and EPSS.
- first-call resolutiontermThe percentage of issues closed in the first contact, no callbacks, no escalation - the metric that best predicts user happiness.
- five ninesjargon99.999% availability - about five minutes of downtime allowed per year.
- five-tupletermThe connection's fingerprint: source IP, source port, destination IP, destination port, protocol - the key by which firewalls, NATs, and balancers track flows.
- flag dayjargonA cutover where everything must change at once, with no coexistence between old and new.
- flappingjargonAn interface or route that keeps going down and up, down and up - never quite dead, never quite stable.
- FLOSSacronymAn umbrella term for software that is both free (as in freedom) and open source.
- flow logstermThe cloud's NetFlow: records of accepted and rejected connections per interface, subnet, or VPC - who talked to whom, and who was refused.
- foo / barloreThe canonical placeholder names in programming examples, used when the specific name does not matter.
- footgunjargonA feature or API so easy to misuse that it invites you to shoot yourself in the foot.
- forklift upgradejargonAn upgrade so total that the old equipment leaves on a forklift - nothing is reused, everything is replaced.
- Fortinet CommunitytermFortinet's official user community - forums, knowledge-base articles, and ideas exchange for the FortiGate ecosystem.
- forward proxytermA server that sits in front of clients and forwards their outbound requests.
- forward secrecytermA property that keeps past sessions safe even if the server's long-term key is later stolen.
- Forwarding profiletermZCC's traffic-plumbing document: for each network state (on/off/VPN trusted) it assigns the forwarding action - Z-Tunnel 1.0/2.0, Tunnel with Local Proxy, Enforce Proxy, or None for ZIA; Tunnel or None for ZPA.
- FPGAacronymField-Programmable Gate Array: a chip whose logic can be rewired after it is manufactured.
- FQDNacronymA complete domain name that specifies a host's exact location in DNS.
- Frame RelaytermThe packet-switched WAN service that replaced X.25 and defined enterprise connectivity in the 1990s and 2000s.
- FREAKloreA 2015 attack forcing servers to use weak, factorable export-grade RSA keys.
- free as in beerexpressionThe disambiguation of 'free software': gratis (free beer) versus libre (free speech) - price versus liberty.
- frobnicatejargonTo fiddle with a setting or object, adjusting it without deep intent - classic hacker-dictionary vocabulary.
- FTPacronymAn old, unencrypted protocol for transferring files between hosts.
- FTPSacronymFTP wrapped in TLS to encrypt the control and data channels.
- FTTHacronymFiber to the Home: optical fiber running the entire last mile into the residence, with no copper or coax remainder.
- FUBARloreSlang for something broken beyond any reasonable repair.
- FUDacronymA tactic of spreading fear, uncertainty, and doubt to undermine a competitor or idea.
- full tablejargonThe complete set of internet routes, taken over BGP from a transit provider - the whole map, not a summary.
- full-disk encryptiontermEncrypting the entire drive so a lost or stolen machine leaks nothing - BitLocker, FileVault, LUKS - unlocked at boot, transparent after.
- Furukawa (Lightera)termFurukawa Electric LatAm - the name on Brazil's structured cabling for decades: the Curitiba-based operation of Japan's 1884-founded Furukawa Electric, whose cabling brand now carries the Lightera name.
- fusion splicetermJoining two fibers by melting them together in an arc - the lowest-loss, permanent way to connect glass, at about 0.02 dB.
- fuzzingtermFeeding a program vast quantities of malformed or random input to see what makes it crash.
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- Gall's lawexpressionA complex system that works is invariably found to have evolved from a simple system that worked.
- GambiarraloreDisputed / commonly mistoldBrazilian Portuguese, feminine noun. An improvised fix built from whatever is to hand — precarious, unorthodox, and working. The word carries admiration and disapproval at the same time, and Brazilians hear both.
- Garoa Hacker ClubeloreSao Paulo's hackerspace - one of Brazil's first, and the room where BSidesSP was born.
- GCMacronymAn AEAD mode that turns AES into an authenticated cipher using a counter and a nonce.
- GDBacronymThe GNU debugger: it runs a program under control so you can stop it, inspect it, and step through it.
- GDPRacronymThe European Union's comprehensive data protection law, in force since 2018.
- generative AItermSystems that produce new text, images, audio or code rather than classifying or ranking existing material.
- GIGOacronymGarbage in, garbage out: no computation improves the quality of its inputs.
- Global Privacy ControltermA browser signal declaring 'do not sell or share my data' automatically on every site - opt-out as a setting instead of a per-site chore.
- Go To Statement Considered HarmfulloreDijkstra's 1968 letter arguing that unrestricted goto makes programs hard to reason about.
- god boxjargonA single appliance that does everything - routing, firewalling, VPN, IPS, load balancing - one box to rule them all.
- Godwin's lawexpressionThe adage that as an online argument grows longer, a comparison to Nazis becomes inevitable.
- gold-platingjargonAdding polish and features nobody asked for - effort spent past the point where the requirement was met.
- golden imagetermThe blessed master build of an operating system plus standard apps and settings, cloned onto every new machine.
- Goodhart's lawexpression'When a measure becomes a target, it ceases to be a good measure.'
- goodputjargonThe throughput that actually matters: useful application data delivered, after all the overhead and retransmissions.
- googolloreThe digit one followed by a hundred zeros, and the word Google is a misspelling of it.
- GOPHERacronymA pre-web protocol for browsing menus of documents.
- GOSIPacronymGovernment OSI Profile: a procurement mandate requiring OSI protocols in government purchases.
- GPOacronymGroup Policy Object: Windows domain settings pushed centrally to users and machines - wallpaper to password policy, mapped drives to lockdown.
- GPONacronymGigabit Passive Optical Network: one fiber from the OLT is split passively among up to 64 or 128 subscribers, sharing 2.5 Gbps down and 1.25 up.
- graceful degradationtermDesigning a system so that when part of it fails, the rest keeps working in a reduced way.
- gray failurejargonA failure that is real but not clean - the system is degraded in a way the health checks do not see.
- GREacronymGeneric Routing Encapsulation: the minimal IP-in-IP envelope (24 bytes with its delivery header, protocol 47) - no encryption, no authentication, just carriage.
- GRE tunnelacronymGeneric Routing Encapsulation: wraps one packet inside another so traffic can cross networks that could not route it natively - a tunnel, without encryption.
- GREASEloreA mechanism that sends random dummy values to keep TLS implementations tolerant of unknown extensions.
- greenfield vs. brownfieldexpressionBuilding on an empty field versus building inside what already exists - the two starting conditions of every project.
- Greenspun's tenth ruleexpression'Any sufficiently complicated C or Fortran program contains an ad hoc, informally-specified, bug-ridden, slow implementation of half of Common Lisp.'
- grokexpressionTo understand something so completely that it becomes part of how you think.
- GSLBacronymGlobal Server Load Balancing: DNS-level traffic steering across sites and regions - answering each resolver with the healthiest, closest, or least-loaded destination.
- GTS / GTERtermNIC.br's twin working groups - GTS for network security, GTER for network engineering and operations: the free meetings where Brazil's internet operators compare notes, twice a year, for decades.
- GUIacronymA visual, point-and-click interface to software.
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- H2HCloreHackers to Hackers Conference: Latin America's oldest security research conference - Sao Paulo, every year since 2004.
- hackloreOriginally, an inventive or elegant solution admired for its cleverness, not a break-in.
- hairpin NATjargonReaching your own public address from inside your own network - the traffic goes out to the NAT and hairpins straight back in.
- halt and catch fire (HCF)loreDisputed / commonly mistoldA jokingly named machine instruction said to make a CPU seize up - and, on some chips, a real undocumented opcode that does.
- handovertermTransferring a problem to another person or team, along with the state of understanding that goes with it.
- Hanlon's razorexpressionThe heuristic to never attribute to malice what is adequately explained by stupidity or mistake.
- hash collisiontermWhen two different inputs produce the same hash output.
- hash functiontermA one-way function that turns any input into a fixed-size fingerprint.
- Have I Been PwnedtermA free service that tells you whether your email or password has appeared in a known data breach.
- have you tried turning it off and on again?expressionSupport's opening liturgy and its most statistically justified question: a restart clears the accumulated state where most transient faults live.
- HDLCacronymHigh-Level Data Link Control - the ISO framing standard that underlies a whole family of serial protocols.
- health checktermThe probe that decides whether a target receives traffic - an endpoint answering 'am I alive?' on a timer, with consequences.
- HeartbleedloreThe 2014 OpenSSL flaw that let attackers read chunks of a server's memory, including keys and passwords.
- heisenbugloreA bug that changes behaviour or disappears when you try to observe it.
- hello, worldloreThe tiny program that just prints a greeting, traditionally the first thing you write in a new language.
- HFacronymHigh frequency, 3 to 30 MHz: the shortwave range where signals refract off the ionosphere and travel worldwide.
- HFCacronymHybrid Fiber-Coaxial: the cable-TV plant architecture - fiber from the headend to neighborhood nodes, coaxial for the final drop - that DOCSIS turned into a shared broadband network.
- HIPAAacronymThe US healthcare-privacy law governing protected health information (PHI).
- HITBloreHack In The Box - the 'deep-knowledge' security conference born in Kuala Lumpur in the early 2000s, whose stages have moved across Asia, Europe, and the Middle East.
- HMACacronymA way to prove a message is authentic and unaltered, using a hash and a shared secret.
- Hofstadter's lawexpressionThe self-referential rule that things always take longer than you expect, even accounting for this rule.
- honeypottermA decoy system built to be attacked: no legitimate user ever touches it, so every interaction is a signal.
- hope is not a strategyexpressionThe SRE reminder that wishing a system stays up is not the same as engineering it to.
- host-to-hosttermA direct association between two endpoints, with no intermediary acting as the resource.
- host-to-multihosttermOne sender reaching many receivers at once: the one-to-many communication pattern.
- Hot / cold aisletermThe data-center layout that keeps equipment intake air separate from exhaust - rows face front-to-front and back-to-back.
- hot / warm / cold standbyexpressionThe three temperatures of a backup system: running and synchronized, running but behind, or powered off until needed.
- hotfixtermAn urgent, narrowly scoped fix shipped outside the normal release cycle.
- HOTPacronymA one-time code advanced by a counter rather than a clock.
- HQCacronymA code-based post-quantum key-encapsulation algorithm selected by NIST as a backup.
- HS256acronymA JWT signing algorithm: HMAC with SHA-256.
- HSMacronymHardware Security Module: a tamper-resistant device that generates, holds, and uses keys internally - the keys can be used but never extracted.
- HSTSacronymA header that forces browsers to use HTTPS for a site.
- HTTP QUERY methodtermThe HTTP method standardized in June 2026 (RFC 10008) for read-only queries that carry a request body: safe and idempotent like GET, body like POST, cacheable with the body in the cache key.
- hub-and-spokeexpressionThe topology where everything connects through a central hub instead of to each other - fewer links, central control, one very important middle.
- hybrid topologytermAny real network: a mix of topologies stitched together, chosen per layer for what that layer needs.
- HyperlinktermA reference from one document to another that a reader can follow directly, and the mechanism the web is built on.
- Hyrum's lawexpressionWith enough users, every observable behavior of your system will be depended on by somebody, contract or not.
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- "incognito mode makes you anonymous"loreDisputed / commonly mistoldPrivate browsing deletes local history and cookies when the window closes - nothing more. Websites, employers, and providers see you exactly as before.
- "is it worth the time?"expressionThe question of whether automating a task actually saves more time than it costs to automate.
- IaaS / PaaS / SaaSacronymThe cloud's three service layers: rent the infrastructure, rent the platform, or rent the finished application - each trading control for convenience.
- IAMacronymIdentity and Access Management: who exists, what they may do, and under which conditions - the permission fabric of the cloud.
- IANAacronymThe function that manages global IP, port, and protocol-number assignments.
- ICANNacronymThe body that coordinates the internet's domain-name and number systems.
- ICAPacronymA protocol for handing HTTP content to an external service for adaptation.
- ICCC demonstrationloreThe 1972 public demonstration of the ARPANET at the International Conference on Computer Communication.
- ICMPacronymThe protocol IP uses for error and diagnostic messages, like ping.
- ID-10-T and friendsjargonThe joke 'error codes' for user-caused issues - ID-10-T, PICNIC, layer 8 - support's private shorthand, best kept private.
- IDCMAacronymIndependent Data Communications Manufacturers Association: the trade body for vendors competing with the carriers.
- idempotency keytermA unique token attached to a request so the server can safely ignore accidental duplicates.
- idempotenttermAn operation that has the same effect whether you run it once or many times.
- identity providertermThe party that authenticates the user and asserts the result: in SAML the IdP issues assertions, in OIDC the same role is the OpenID Provider issuing ID tokens.
- IEEEacronymThe engineering society whose 802 committee defines the LAN standards everything on this site runs over.
- IETFacronymThe body that standardizes the internet's protocols, in the open, as RFCs.
- if it hurts, do it more oftenexpressionThe counterintuitive delivery principle: painful, risky activities become safe through frequency, not avoidance.
- IGMPacronymInternet Group Management Protocol - how a host raises its hand for a multicast group, and how the network learns which ports actually want the stream.
- IGPacronymInterior Gateway Protocol - the class of routing protocols that run inside one autonomous system: OSPF, IS-IS, EIGRP, RIP.
- IISacronymMicrosoft's web server software for Windows.
- IKEacronymThe protocol that negotiates keys and security parameters for IPsec VPNs.
- illegal numberloreA number whose mere possession or publication is claimed to be unlawful, the reductio ad absurdum of information control.
- IMAPacronymA protocol for reading email kept on the server, across multiple devices.
- IMAPSacronymIMAP encrypted with TLS.
- IMDSacronymInstance Metadata Service: the link-local endpoint (169.254.169.254) where a cloud instance asks about itself - and collects its temporary credentials.
- immutable infrastructuretermAn approach where servers are never modified in place; to change one, you replace it with a new build.
- IMPacronymInterface Message Processor: the ARPANET's packet switch, a separate minicomputer sitting between a host and the network.
- incastjargonThe many-to-one traffic collapse: dozens of servers answer one request simultaneously and their combined burst overruns the receiver's switch port.
- incidenttermAn unplanned interruption or reduction in quality of a service, as distinct from a request for something new.
- incident vs. service requestexpressionThe great ITIL fork: an incident is something broken; a request is something wanted - different queues, clocks, and expectations.
- Infovia BrasíliatermThe Brazilian federal government's own metropolitan network in Brasília, running on state-owned fibre and operated by Serpro exclusively for public bodies.
- infrastructure as codetermManaging servers and networks through version-controlled configuration files rather than manual setup.
- InmetroacronymBrazil's national metrology, quality and technology institute, responsible for measurement standards and conformity assessment.
- integer overflowtermAn arithmetic result too large for its type, so the value silently wraps around instead of growing.
- inter-frame gaptermThe mandatory idle time between Ethernet frames, 96 bit times, that gives every receiver a beat to reset before the next frame arrives.
- intermittent faulttermA failure that occurs unpredictably and cannot be triggered on demand, so it cannot be tested against directly.
- internet gatewaytermThe VPC component that gives public subnets a door to the internet - horizontally scaled, no bandwidth knob, no single box to fail.
- InteroploreThe trade show that began as a TCP/IP interoperability demonstration and became the industry's proving ground.
- IoCacronymA forensic artifact that indicates a system may have been breached: a hash, an IP, a domain, a filename, a registry key.
- IOS (Cisco)acronymCisco's long-standing operating system for routers and switches.
- IPtermThe best-effort, connectionless delivery layer that addresses and routes packets across interconnected networks, the thin waist every internet application stands on.
- IP transittermPaying a bigger network to reach the whole internet - the ISP's upstream bill, priced per megabit of committed rate.
- IPAMacronymIP Address Management: the system of record for who owns which range - allocations, assignments, and conflicts, tracked instead of remembered.
- IPoEacronymIP over Ethernet: subscriber access without PPPoE - plain DHCP, with identity taken from the line itself rather than a login.
- IPSacronymA control that detects and blocks attacks inline.
- IPsecacronymThe standard suite for encrypting and authenticating IP traffic, powering most site-to-site VPNs; keys are negotiated by IKE.
- IPX/SPXacronymNovell NetWare's networking protocols - the LAN standard of the file-server era, derived from Xerox XNS.
- IRAPacronymAustralia's assessment framework letting cloud services be validated against the government's security manual.
- IS-ISacronymIntermediate System to Intermediate System - OSPF's link-state twin from the OSI world: the protocol you have probably never configured, running the carrier backbones your traffic crosses every day.
- ISC2termThe certification body behind the CISSP - the credential most often gatekeeping senior security roles.
- ISM bandtermIndustrial, scientific and medical bands: spectrum usable without an individual licence, subject to power and interference rules.
- ISO/IEC 27001acronymThe international standard for an information security management system (ISMS) - the certification most vendor trust centers lead with.
- ISO/IEC 27017acronymThe cloud-security extension of ISO 27001 - controls specific to being, or using, a cloud service provider.
- ISO/IEC 27018acronymThe privacy extension of ISO 27001 - protecting personally identifiable information processed in the public cloud.
- ISPacronymA company that provides internet access.
- ISRGacronymThe nonprofit that runs Let's Encrypt.
- IT asset managementtermTracking hardware and software through their whole lifecycle - procurement, assignment, patching, retirement - so licenses, budgets, and audits reconcile.
- it's always DNSexpressionThe troubleshooting proverb that whatever the symptom, the root cause will turn out to be DNS.
- ITILacronymThe IT service management framework - the shared vocabulary of incidents, problems, changes, and services that lets operations teams and their tickets speak one language.
- IVacronymA starting value that makes a cipher produce different output for identical input.
- IXPacronymInternet Exchange Point: the shared switching fabric where dozens or hundreds of networks meet to peer in one place.
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- JA3acronymA fingerprint of a TLS client built from the fields in its ClientHello.
- JA4acronymA newer, more robust family of TLS and network fingerprints.
- JeitinholoreDisputed / commonly mistoldBrazilian Portuguese. The knack of getting something done by going around a rule rather than through it — usually with charm, usually without money changing hands, and usually at a small cost to somebody who is following the rule.
- juice jackingjargonThe attack theory that a public USB charging port could push malware or pull data while it charges your phone.
- jumbo framestermEthernet frames carrying more than the standard 1500-byte payload, typically 9000: fewer headers per gigabyte, and misery when one hop in the path disagrees.
- just-in-time accesstermPrivileges granted for the task and the hour, then automatically revoked - standing admin rights replaced by requested, approved, expiring ones.
- JWICSacronymThe US intelligence community's network for top secret and compartmented information, the most restricted of the three tiers.
- JWKacronymA JSON format for representing a cryptographic key.
- JWKSacronymA published set of keys used to verify signed tokens.
- JWSacronymA standard for signing data represented as JSON.
- JWTacronymA compact, signed token that carries claims about a user, used to prove identity between services.
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- k-anonymitytermA dataset property where every person is indistinguishable from at least k-1 others on the quasi-identifiers - hiding in a crowd of size k.
- KalpanaloreThe Sunnyvale startup that shipped the first multiport Ethernet switch in 1990 and, four years later, became one of Cisco's most consequential acquisitions.
- KanbantermToyota's pull system, adapted to knowledge work: visualize the flow, limit work in progress, and let capacity pull tasks instead of schedules pushing them.
- KDCtermKey Distribution Center: the Kerberos authority - Authentication Service plus Ticket-Granting Service - that verifies principals and issues the TGT and service tickets; in Active Directory it runs on the domain controllers.
- KDFacronymA function that turns a secret into one or more cryptographic keys.
- keep the lights onjargonThe baseline operational work that keeps existing systems running - maintenance, patching, renewals, the unglamorous constant.
- KerberostermThe ticket-based network authentication protocol behind enterprise silent sign-on: a Key Distribution Center issues time-limited tickets that services can verify offline, so passwords travel once at login and never again.
- Kerckhoffs's principleexpressionA cryptosystem must remain secure even if everything about it, except the key, is public knowledge.
- Kernighan's lawexpression'Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it.'
- Kevin MitnickloreThe 1990s hacker whose social-engineering exploits made him the era's most famous computer intruder.
- Kevin PoulsenloreThe hacker who seized a radio station's phone lines to be caller 102 and win a Porsche, then became a security journalist.
- key exchangetermHow two parties agree on the session's secret key - the part of a cipher suite that decides whether recorded traffic stays sealed.
- key rotationtermReplacing cryptographic keys and credentials on schedule, so a stolen secret has an expiry date instead of a lifetime.
- keytabtermA file holding a service account's long-term Kerberos keys, letting a service - often on Linux, outside the domain - decrypt the tickets clients present without interactive domain membership.
- KISSexpressionThe design principle that systems work best when kept simple rather than made complex.
- kludgeloreA clumsy, inelegant fix that works despite being ugly.
- KMSacronymKey Management Service: the managed vault where encryption keys live, guarded by hardware, used via API, and never exported in the clear.
- knowledge basetermThe searchable library of known issues, fixes, and how-tos - support's compound interest, paid into one resolved ticket at a time.
- KRACKloreA 2017 attack on WPA2 Wi-Fi that resets encryption keys to replay traffic.
- KubernetestermAn open-source system for automating the deployment and scaling of containerized applications.
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- L3acronymThe network layer, where IP routing happens.
- L4acronymThe transport layer, handling ports and connections like TCP/UDP.
- L4 vs. L7 load balancingexpressionBalancing on addresses and ports versus on the application itself: L4 is fast and blind, L7 reads HTTP and routes by path, header, or cookie.
- L7acronymThe application layer - where protocols like HTTP live in the OSI model.
- LACNICacronymThe Latin American and Caribbean internet registry - the steward of the region's IP addresses and AS numbers, whose twice-yearly meetings double as the region's operator congress.
- LACPacronymLink Aggregation Control Protocol: bundles multiple physical links into one logical channel for bandwidth and redundancy, negotiated rather than hoped for.
- landing zonetermThe pre-built, governed foundation of a cloud estate: account structure, identity, networking, logging, and guardrails, ready before the first workload.
- LANEacronymLAN Emulation - the ATM Forum's scheme for making a cell network impersonate Ethernet. Famously the moment many engineers decided ATM to the desktop was a bad idea.
- large language model (LLM)acronymA model trained on very large amounts of text to predict what comes next, which turns out to be enough to do a great many other things.
- last miletermThe final stretch of network between the provider's infrastructure and the customer's door - the most expensive kilometers in telecom.
- lateral movementtermSpreading from one compromised system to others across a network.
- LatinowaretermThe Latin American congress of free software and open technologies, held since 2004 at the Itaipu Technology Park in Foz do Iguaçu.
- layer 8jargonThe unofficial OSI layer above application: the human - where a startling share of network problems actually occur.
- LBacronymA device or service that spreads traffic across multiple servers.
- LCSacronymThe longest sequence common to two inputs, keeping order.
- LDAPacronymThe protocol for querying and modifying directory services like Active Directory.
- LDAPSacronymLDAP encrypted with TLS.
- LDNSacronymThe recursive resolver a client actually queries.
- leaf-spinetermThe modern data-center fabric: every leaf switch connects to every spine, giving any two servers the same short predictable path.
- leaky abstractionexpressionAn abstraction that is supposed to hide complexity but lets details of what is underneath show through.
- least privilegetermGiving each user or process only the access it needs to do its job, and no more.
- left-padloreThe eleven-line npm package whose 2016 removal broke builds across the JavaScript world.
- legitimate interesttermThe lawful basis for processing without consent when the controller's genuine need outweighs the person's rights - after a documented balancing test.
- LEO constellationtermA fleet of satellites in Low Earth Orbit - hundreds of kilometers up rather than geostationary's 35,786 km - trading one motionless satellite for thousands of moving ones: latency drops to tens of milliseconds, at the cost of constant handoffs, phased-array terminals, and fleet logistics. Starlink is the operating example at scale.
- LGPDacronymLei Geral de Proteção de Dados: Brazil's general data protection law (13.709/2018), governing personal data processing on GDPR-inspired principles with Brazilian teeth.
- LGTMacronymThe code-review approval stamp: looks good to me.
- lift and shiftjargonMigrating a workload to the cloud exactly as it is - same VM, same architecture, new landlord.
- link-local addresstermAddresses valid only on the local segment: IPv6's fe80::/10 on every interface by design, IPv4's 169.254.0.0/16 usually meaning DHCP failed.
- Linus's lawexpression'Given enough eyeballs, all bugs are shallow.'
- lit fiberjargonFiber with the electronics attached and light flowing - a working service, as opposed to dark fiber you light yourself.
- living off the landjargonAttacking with the tools already installed on the victim's systems, so nothing malicious ever has to be downloaded.
- LLDPacronymLink Layer Discovery Protocol: neighbors introduce themselves on the wire - device, port, capabilities - turning 'what is on the other end?' into a show command.
- LLMacronymA neural network trained on vast text that generates and understands language.
- load balancingtermSpreading incoming work across several servers so no one server is overwhelmed.
- Log4ShellloreThe 2021 vulnerability in the ubiquitous Log4j logging library that let a logged string execute arbitrary code.
- LogjamloreA 2015 attack downgrading Diffie-Hellman key exchange to weak 512-bit export parameters.
- longest prefix matchtermThe routing rule that the most specific matching prefix wins: /32 beats /24 beats /0, regardless of protocol or metric.
- looking glassjargonA public web interface into a network's router, letting outsiders run ping, traceroute, and BGP queries from inside that network.
- loopback interfacetermA virtual interface that never goes down, giving the router a stable identity for routing protocols and management regardless of physical link state.
- LoRatermA long-range, low-power radio technique (Semtech's chirp spread spectrum) and, via LoRaWAN (the LoRa Alliance's network specification), an LPWAN architecture: kilometers of range, years of battery, bytes of payload, gateways forwarding whatever they hear.
- Lucky ThirteenloreA 2013 timing attack against CBC padding in TLS.
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- "MAC addresses are unique and permanent"loreDisputed / commonly mistoldThe burned-in address stopped being either: operating systems randomize Wi-Fi MACs per network by default, and any MAC can be set in software in seconds.
- "more bandwidth means a faster connection"loreDisputed / commonly mistoldBandwidth is lane count; latency is trip time. Past a modest threshold, page loads, calls, and games are ruled by latency and bufferbloat - which a bigger plan does not fix.
- MAC (message authentication code)acronymA short tag that proves a message came from someone holding the shared key and was not altered.
- MAC addresstermThe hardware address that identifies a network interface on a local network.
- MAC flappingtermThe same MAC address appearing rapidly on different switch ports - the signature of a loop, a bad bond, or a device bridging where it should not.
- magic numberjargonAn unexplained constant buried in code, or the signature bytes that identify a file format.
- magic smokejargonThe smoke inside electronics that, once released, can never be put back - the joke explanation for why fried hardware stays dead.
- maintenance windowtermThe scheduled low-impact period when changes are allowed - announced, bounded, and rollback-planned; work outside it needs an emergency's justification.
- make it work, make it right, make it fastexpressionKent Beck's ordering of concerns: first correctness, then design, then - and only then - speed.
- mandelbugjargonA bug whose causes are so complex and tangled that its behavior looks chaotic or nondeterministic.
- martian packettermA packet whose source or destination address could not legitimately appear where it did, as if it arrived from Mars.
- MCPacronymAn open protocol that lets AI models call external tools and data sources in a standard way.
- MD5acronymAn old 128-bit hash function, cryptographically broken and unsafe for security use.
- MDF / IDFacronymMain and Intermediate Distribution Frames: the building's cabling hierarchy - everything homes to the MDF, floors terminate in IDFs.
- MDMacronymMobile Device Management: enrolling phones, tablets, and laptops under central policy - configure, patch, locate, and wipe from one console.
- MDNacronymMozilla's widely used web-technology documentation site.
- Media convertertermThe small box that translates one physical medium to another - classically copper Ethernet to fiber and back.
- meet-me roomjargonThe room in a carrier-neutral facility where networks physically interconnect - the cross-connect floor where the internet is literally patched together.
- MeltdownloreA 2018 attack letting user programs read protected kernel memory via speculative execution.
- memory leaktermMemory that a program allocates and never releases, so its footprint grows until something gives.
- memory safetytermThe property of never accessing memory outside what a program legitimately owns, in space or in time.
- Mente BináriatermThe Brazilian nonprofit teaching computing and security from first principles - free courses, an active forum, and open-source tooling.
- Merkle treetermA tree of hashes that lets you verify one item belongs to a large set efficiently.
- mesh topologytermNodes connect to many other nodes directly, so traffic has multiple independent paths.
- mesh Wi-FitermMultiple cooperating access nodes forming one seamless network, relaying wirelessly where cable cannot reach.
- metadatatermData about data: who contacted whom, when, from where, how often - everything except the content, and often more revealing than it.
- Metcalfe's lawexpressionThe value of a network grows with the square of its number of connected users.
- MFAacronymRequiring two or more independent proofs of identity to log in, not just a password.
- microburstjargonA traffic spike so brief that it overflows a switch buffer and drops packets, yet vanishes inside the utilization averages.
- MicrocodetermA layer inside a processor that implements its published instruction set in terms of simpler internal operations.
- microsegmentationtermDividing a network into small, individually controlled zones to limit lateral movement.
- MicrotunneltermZPA's per-application, per-user-session thread riding inside the TLS connections from client and App Connector, stitched at a Service Edge.
- middle milejargonThe network segment between the local access network and the internet's core - the haul from the neighborhood to the exchange.
- MIMEacronymA standard for labeling the type of a piece of content.
- Mind the SectermThe corporate-scale information-security conference of Sao Paulo - where the Brazilian market's decision-makers meet the vendor ecosystem.
- MirailoreA 2016 botnet that hijacked IoT devices to launch record DDoS attacks.
- MITREtermThe US not-for-profit that operates federally funded R&D centers - and, for practitioners, the home of ATT&CK, CVE, and CWE.
- mixer (tumbler)termA service that blends many parties' cryptocurrency together to obscure who paid whom.
- ML-KEMacronymThe NIST-standardized post-quantum key-encapsulation algorithm.
- Moore's lawexpressionThe observation that the number of transistors on a chip roughly doubles every couple of years.
- Morse code / CWtermEncoding of characters as short and long tones, sent as an on-off keyed carrier and known on the air as CW.
- move fast and break thingsexpressionA mantra prizing speed and iteration over caution, accepting that some breakage is the cost of learning fast.
- MPLSacronymMultiprotocol Label Switching - forwarding by short labels instead of IP lookups: push a label at the edge, swap it hop by hop, pop it before the exit. The machinery under most carrier services.
- MQTTacronymA lightweight publish-subscribe protocol for IoT and telemetry.
- MQTTSacronymMQTT encrypted with TLS.
- MSRDPacronymMicrosoft's protocol for remote graphical desktop sessions.
- MSSacronymThe largest chunk of actual data a TCP segment carries, after headers.
- MSS clampingexpressionRewriting TCP's advertised Maximum Segment Size downward in the SYN so segments fit a tunnel's reduced MTU without fragmentation or black holes.
- Mt. GoxloreThe Tokyo exchange that handled most of the world's bitcoin trades until 850,000 of them vanished in 2014.
- MTTRacronymMean Time To Repair: the average clock from failure to restoration - the operational number behind every SLA repair promise.
- MTUacronymThe largest packet, in bytes, a link will carry without fragmenting.
- multicasttermOne-to-many delivery: a single transmission sent to a group address reaches every host that joined the group, and only them.
- multihost-to-hosttermMany senders converging on one receiver: the many-to-one pattern, also called incast.
- Multilink PPPacronymMultilink PPP - bundling several physical links into one logical PPP connection for more bandwidth.
- Multimode fibertermThe short-reach fiber of buildings and data centers - a wide core, cheaper optics, distances of hundreds of meters.
- mungjargonTo transform data through a series of changes, often messily or destructively.
- Murphy's lawexpression'Anything that can go wrong will go wrong' - engineering's oldest planning assumption.
- MWCacronymMobile World Congress - the GSMA's Barcelona mega-show where the telecom industry announces its year: handsets, networks, and roughly a hundred thousand badge-wearers.
- MXacronymThe DNS record that says which servers receive a domain's email.
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- "NAT is a firewall"loreDisputed / commonly mistoldThe belief that address translation is a security control. NAT hides topology as a side effect, but it filters nothing by policy - a stateful firewall does.
- nanotermA small, unmodal terminal editor that shows its own shortcuts along the bottom of the screen.
- NANOGacronymThe North American Network Operators' Group: the town hall where the people who actually run the internet compare notes - three meetings a year and one legendary mailing list, since 1994.
- NATacronymRewriting IP addresses in transit, classically to let many private hosts share one public address.
- NAT gatewaytermThe managed service that lets private subnets reach out to the internet without being reachable from it - outbound yes, inbound no.
- NAT-TacronymNAT Traversal: IPsec's repair for address translation - detecting NAT in IKE and re-wrapping ESP in UDP/4500 so per-flow ports exist again.
- NCPacronymNetwork Control Program: the ARPANET host protocol that TCP/IP replaced.
- nerd snipejargonPresenting someone an irresistibly interesting problem, derailing whatever they were supposed to be doing.
- NetFlowtermFlow telemetry: routers export who-talked-to-whom records (addresses, ports, bytes, duration) so you can see traffic patterns without capturing packets.
- network ACL (cloud)acronymThe stateless subnet-level filter in cloud networks: numbered allow and deny rules evaluated in order, both directions filtered independently.
- network topologytermThe shape of a network: how nodes are connected, drawn either as the cables actually run or as the traffic actually flows.
- never touch a running systemexpressionThe conservative operator's creed: if it works, leave it alone.
- NewEdgetermNetskope's privately operated global network of data centers - the infrastructure the Netskope One security cloud runs on. Every data center provides full compute for single-pass inspection, with extensive peering close to users and to the major SaaS providers.
- NFVacronymNetwork Functions Virtualization: firewalls, routers, and gateways as software on standard servers instead of dedicated appliances.
- NIC.brloreNúcleo de Informação e Coordenação do Ponto BR: the entity that implements CGI.br's decisions - formalized in 2003, operating the .br registry (Registro.br) since 2005, plus measurement, IX, and security functions.
- NICE Framework Work Role CategoriestermThe five high-level groupings the NICE Framework uses to organise cybersecurity work: Oversight and Governance, Design and Development, Implementation and Operation, Protection and Defense, and Investigation.
- NimdaloreThe September 2001 worm that attacked through five vectors at once, a week after 9/11.
- NIPRNetacronymThe unclassified but sensitive network of the US Department of Defense, and the one with controlled connections to the public internet.
- NIS2acronymThe EU directive massively expanding cybersecurity obligations across essential and important sectors.
- NISTacronymThe US standards agency whose cryptographic and security publications function as global engineering baselines.
- NIST CSF (Cybersecurity Framework)acronymThe NIST Cybersecurity Framework: a voluntary structure for organising security work around a small set of high-level functions.
- NIST CSRC (Computer Security Resource Center)acronymThe Computer Security Resource Center, NIST's publication hub for its security standards, guidance and reference data.
- no plan survives contactexpressionMoltke's maxim: the plan is what you have until reality responds, then adaptation is the actual skill.
- no silver bulletexpressionFred Brooks's claim that no single technique will yield an order-of-magnitude gain in software productivity, because complexity is essential, not accidental.
- node splittermDividing a congested cable or PON serving area into two smaller ones, halving the subscribers who share the same capacity.
- noisy neighborjargonA tenant whose heavy resource use degrades performance for others sharing the same infrastructure.
- noncetermA number used once, included in a protocol so the same message cannot be replayed.
- not invented hereexpressionThe bias toward building something yourself rather than adopting a perfectly good external solution.
- NotPetyaloreA 2017 destructive malware outbreak disguised as ransomware.
- NSECacronymA DNSSEC record that proves a name does not exist.
- NSEC3acronymA hashed version of NSEC that hides a zone's contents.
- NTLMacronymA legacy Microsoft challenge-response authentication protocol.
- NTPacronymThe Network Time Protocol: the protocol that keeps clocks across a network agreeing with each other, and with the rest of the world.
- nuke and pavejargonTo stop debugging a sick machine and simply wipe it and reinstall from scratch.
- null pointer dereferencetermFollowing a pointer that holds null, so the program reads or writes address zero and is stopped by the operating system.
- NullconloreIndia's flagship hacker conference, grown out of null - the country's largest open security community - and held on the beaches of Goa since 2010.
- number portingtermMoving a phone number between carriers while keeping it - a regulated right, a database update, and a fraud vector when hijacked.
- NVDacronymThe US government's public database of known vulnerabilities.
- NX bit / DEPtermMarking memory pages as either writable or executable, but never both, so injected data cannot run as code.
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- OAuthtermA standard that lets an app access your data on another service without handling your password.
- observabilitytermHow well you can understand what a system is doing internally from the signals it emits.
- observer effecttermWhen the act of measuring changes the behaviour being measured, so the fault disappears while you are watching for it.
- OC levels (OC-3 to OC-768)termThe SONET Optical Carrier ladder - OC-3, OC-12, OC-48, OC-192 - every rung 51.84 Mb/s times n, with SDH's STM names for the same speeds.
- OCSPacronymA protocol to check in real time whether a certificate has been revoked.
- off-by-one errorloreThe classic error of counting one too many or one too few, especially at the boundaries of a loop or range.
- OGNL (Object-Graph Navigation Language)acronymAn expression language for reading and writing Java object properties, used as a configuration feature by some products and as an attack vehicle against others.
- OIDCacronymAn identity layer on top of OAuth 2.0 for authenticating users.
- OKRacronymObjectives and Key Results - Andy Grove's goal-setting discipline from Intel: a qualitative ambition, measured by a few brutally quantitative results.
- OLTacronymOptical Line Terminal: the provider-side head of a PON, terminating hundreds of subscriber fibers and scheduling every upstream burst.
- on the internet, nobody knows you're a dogexpressionThe 1993 New Yorker cartoon that named the internet's founding identity condition: online, nobody can tell who or what you are.
- onboarding / offboardingexpressionThe account-and-access lifecycle at hiring and departure: created and granted on day one, revoked completely on the last - the second half is the audit finding.
- onion routingtermA privacy technique that wraps traffic in layers of encryption and bounces it through several relays.
- ONTacronymOptical Network Terminal: the customer-side box that converts the PON's light into Ethernet - the fiber modem, in everyday speech.
- Open GraphtermA small set of HTML meta tags that tell other sites how to display a link to your page - the title, image, and description in the preview card.
- OpenTokentermPing Identity's encrypted token format for integration kits: the authenticated identity travels between PingFederate and an application as an OpenToken carried by cookie, query parameter, or POST.
- Operation AuroraloreThe 2009 espionage campaign against Google and dozens of companies that dragged nation-state hacking into the open.
- OPSECacronymThe discipline of protecting the small pieces of information that together reveal too much.
- OPTacronymA pseudo-record that carries EDNS options in a DNS message.
- opt-in vs. opt-outexpressionThe two default postures of consent: nothing happens until you say yes, versus everything happens until you say no - defaults decide outcomes at population scale.
- optical power budgettermThe decibels a link can afford to lose between transmitter and receiver; splitters, splices, connectors, and distance all spend from it.
- optical splittertermThe passive glass component that divides one PON fiber into many - no power, no electronics, just engineered light loss.
- OSINETacronymA testbed network for checking that OSI implementations from different vendors actually interoperated.
- OSPFacronymOpen Shortest Path First: the standard link-state interior routing protocol, in which every router maps the whole area and computes shortest paths.
- OTDRacronymOptical Time-Domain Reflectometer: fires light pulses down a fiber and reads the reflections, mapping every splice, bend, and break by distance.
- OTPacronymA password valid for a single login or a short window.
- out-of-band managementexpressionA separate management path - console servers, dedicated ports, even 4G - that still works when the production network is the thing that broke.
- oversubscriptiontermSelling or provisioning more aggregate capacity than the uplink actually has, betting that everyone never peaks at once - a ratio, and a promise.
- OWASPacronymA nonprofit community that produces free, widely used guidance on application security.
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- "public Wi-Fi means instant hacking"loreDisputed / commonly mistoldA decade-old truth gone stale: with HTTPS now near-universal, the café network sees hostnames, not contents. The realistic risks shrank to fake portals, rogue twins, and the rare unencrypted service.
- PACacronymA JavaScript file that tells a browser which proxy to use per URL.
- PagertermA one-way radio receiver on a simulcast broadcast network - the bip: no transmitter, no uplink, everything in range decoded and only your address displayed. Classic service relayed messages through human operators; POCSAG and FLEX carried the digital formats.
- PageRanktermGoogle's ranking idea: score a page by who links to it, weighting links from well-linked pages more heavily.
- PAPacronymThe Password Authentication Protocol - PPP's simplest, and least safe, way to log in: the password in plaintext.
- Parkinson's lawexpression'Work expands so as to fill the time available for its completion.'
- Password Credential ValidatortermPingFederate's reusable password-checking component: given a username and password, a PCV answers valid or invalid against a source such as an LDAP directory - and adapters consume it rather than users meeting it directly.
- password managertermA vault that generates and stores a unique strong password per site, unlocked by one master secret - the practical end of password reuse.
- patchtermA change applied to existing software to fix a defect or close a vulnerability.
- patch managementtermThe cycle of testing and deploying software updates across the fleet - balancing the risk of the bug against the risk of the fix.
- patch paneltermThe passive frame where permanent cabling terminates in numbered jacks, so changes happen with patch cords instead of a punch-down tool.
- Patch Tuesday, Exploit WednesdayexpressionThe rhythm of Windows security: fixes ship on the second Tuesday, and reverse-engineered attacks follow within days.
- Path MTU DiscoveryacronymHow a sender finds the smallest MTU along the whole route, not just the first hop.
- payloadtermThe part of an attack that carries out the intended action, once delivery succeeds.
- pcap or it didn't happenexpressionThe network engineer's evidence standard: claims about traffic are settled by a packet capture, not by opinion.
- PCI DSSacronymThe payment-card industry's security standard for anyone who stores, processes, or transmits cardholder data.
- PDFacronymA fixed-layout document file format.
- PEBKACacronymHelpdesk code for 'the problem exists between keyboard and chair': the user.
- peer-to-peertermAn architecture where every node is both client and server, providing resources to the others directly.
- peeringtermTwo networks exchanging each other's customer traffic directly, usually settlement-free - because both save on transit.
- PEMacronymA Base64 text wrapper for certificates and keys, with BEGIN/END lines.
- penetration testtermAn authorized simulated attack that finds weaknesses before a real attacker does.
- peppertermA secret value added alongside the salt when hashing passwords.
- percussive maintenancejargonThe time-honored art of fixing a device by striking it firmly - occasionally effective on oxidized contacts, always effective on morale.
- perfect is the enemy of goodexpressionVoltaire's warning that pursuing the flawless blocks shipping the sufficient.
- phishingtermTricking someone into revealing credentials or running malware, usually by email.
- PhrackloreThe underground e-zine, published since 1985, that carried hacker culture's founding texts and its deepest technical writing.
- PIIacronymAny data that can identify a specific person, on its own or combined with other data.
- PIMacronymProtocol Independent Multicast - the routing of multicast: building the delivery trees that carry one stream to many networks, using whatever unicast routing table already exists.
- PINacronymA short numeric secret used to authenticate a person.
- pizza boxjargonA flat 1U rack-mount server or switch - the form factor of a large pizza, stacked by the dozen.
- PKCEacronymAn OAuth extension that protects the authorization-code flow.
- PKIacronymThe system of certificates and authorities that lets strangers trust each other's public keys.
- Plenum-rated cabletermThe fire rating that decides where a cable may legally run - plenum (CMP) for air-handling spaces, riser (CMR) for vertical shafts.
- PMTUDacronymPath MTU Discovery: sending with Don't Fragment set and shrinking on ICMP Fragmentation Needed replies - which over-filtered networks silently break.
- podtermThe smallest deployable unit in Kubernetes: one or more containers that share networking and storage.
- PoEacronymPower over Ethernet: the switch feeds power down the data cable, so phones, cameras, and access points need no outlet.
- PoE injectortermThe midspan device that adds Power over Ethernet to a link whose switch cannot supply it.
- Poe's lawexpressionWithout a clear marker of intent, parody of extreme views is indistinguishable from the views themselves.
- pole attachmenttermThe regulated right to hang cables on utility poles owned by power or phone companies - rented space, strict rules, long queues.
- POODLEloreA 2014 attack that forces a downgrade to SSL 3.0 to exploit its broken CBC padding.
- PoPacronymPoint of Presence: a provider's physical edge site - where the CDN caches, the transit hands off, and the backbone touches the ground.
- POP3acronymAn older, simple protocol for downloading email from a server.
- port mirroring (SPAN)termCopying a port's or VLAN's traffic to another port so an analyzer or IDS can watch without sitting inline.
- port securitytermSwitch-port rules limiting which and how many MAC addresses may appear, so a rogue hub or spoofed device trips the port instead of joining it.
- PoSacronymPacket over SONET - IP straight onto the optical hierarchy in PPP framing, skipping ATM's cell tax. The backbone link of the early-2000s internet core.
- POSIXacronymA standard defining a portable interface for Unix-like operating systems.
- post-incident reviewtermThe meeting or document that examines an incident after service is restored, to decide what changes as a result.
- post-quantum cryptographytermNew algorithms designed to stay secure even against a future large-scale quantum computer.
- Postel's lawexpression'Be conservative in what you do, be liberal in what you accept from others' - the robustness principle from the TCP specification.
- postmortemtermA written account, after an incident is resolved, of what happened and what should change.
- Posture profiletermA named device-state check evaluated by Zscaler Client Connector - disk encryption, OS state, certificate presence, and similar signals - consumed by ZPA access rules as conditions and surfaced to ZIA as device trust.
- POTSacronymPlain Old Telephone Service: the analog telephone network - a voice in the 300-3400 Hz band over a dedicated twisted pair for the duration of a call. Dial-up internet was data squeezed through its voice channel, one occupied line at a time.
- PPPacronymThe Point-to-Point Protocol - the standard way to run IP (and more) over a serial link, from dial-up to modern broadband.
- PPPoEacronymPoint-to-Point Protocol over Ethernet: wraps each subscriber's traffic in an authenticated session, so the ISP knows who you are before routing you.
- premature optimizationexpressionTuning code for speed before you know it matters, at the cost of clarity and time.
- PRFacronymA function that stretches a secret into as much key material as a protocol needs.
- PRIacronymThe leading field in a syslog message encoding facility and severity.
- PrintNightmareloreA 2021 set of flaws in the Windows Print Spooler enabling remote code execution.
- PrismatermPalo Alto Networks' cloud-security family, announced in May 2019: securing cloud workloads, cloud access, and the WAN that reaches them.
- privacy by designtermBuilding data protection into systems from the first sketch - minimization, defaults, and safeguards as architecture, not as patches.
- privacy-enhancing technologiestermThe toolbox that lets data be used while exposing less of it: differential privacy, homomorphic encryption, secure multiparty computation, federated learning.
- private DNS zonetermDNS names that resolve only inside your VPCs - internal service names invisible to the public internet.
- private endpoint / PrivateLinktermConsuming a service through a private address inside your own VPC, so the traffic never touches the public internet.
- Private Service EdgetermA ZPA Service Edge instance the customer hosts in their own environment, brokering the same stitched Microtunnels as the cloud's Public Service Edges but keeping the meeting point local.
- privilege escalationtermTurning limited access into greater access, ideally administrator or root.
- problem managementtermThe ITIL practice that hunts the cause behind recurring incidents: incidents restore service, problems remove the reason it broke.
- profilingtermAutomated evaluation of a person from their data - predicting behavior, interests, reliability, movement - the model of you that decisions get made against.
- Project MACloreThe MIT time-sharing research project whose people and ideas seeded much of computer communications.
- promiscuous modetermA network interface setting that accepts every frame on the wire, not just those addressed to it.
- provisioningtermThe automated chain that turns a signed contract into a working service: records created, equipment authorized, speed profile applied.
- ProxyLogonloreA 2021 chain of Microsoft Exchange flaws exploited widely in the wild.
- ProxyShellloreA 2021 Exchange exploit chain related to ProxyLogon.
- pseudonymizationtermReplacing identifiers with pseudonyms while keeping the mapping elsewhere - reversible by design, protective in the meantime.
- PSSacronymA randomized RSA signature scheme, more robust than the older deterministic padding.
- PTP (Precision Time Protocol)acronymPrecision Time Protocol, IEEE 1588: time synchronisation to sub-microsecond accuracy, achieved by putting timestamps in hardware rather than software.
- PTRacronymA DNS record that maps an IP address back to a hostname.
- Public Service EdgetermZscaler's enforcement node in its worldwide data centers: terminates sessions, applies identity and policy, originates the onward connection; packet data stays in memory, never on disk.
- public vs. private subnetexpressionThe basic VPC split: public subnets route to the internet gateway and can be reached; private subnets reach out through NAT and cannot.
- public-key cryptographytermEncryption using a pair of keys, one public and one private, so no shared secret must be exchanged first.
- purple teamtermRed and blue working together, so every offensive finding immediately improves the defence.
- purpose limitationtermData collected for one stated purpose may not be quietly reused for another - the principle that keeps datasets from wandering.
- PVAacronymF5 hardware that accelerates simple Layer 4 traffic.
- pwnedloreSlang for having been thoroughly defeated or compromised.
5
- "quantum computers will break all encryption"loreDisputed / commonly mistoldShor's algorithm threatens today's public-key math (RSA, elliptic curves) on a large fault-tolerant quantum computer - which does not yet exist. Symmetric ciphers and hashes mostly just double their key sizes.
- QAacronymThe discipline of building confidence that software does what it should, before users find out otherwise.
- QATacronymIntel hardware that offloads cryptography and compression from the CPU.
- QoSacronymTechniques that prioritize some network traffic over others to meet performance needs.
- QRacronymA 2D barcode that phones scan to read data quickly.
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- rabbit holeexpressionAn investigation that keeps pulling you deeper, well past where you meant to stop.
- RaccoonloreA 2020 timing attack on TLS-DH that can recover the session key in rare cases.
- race conditiontermA bug where the outcome depends on the unpredictable timing of concurrent operations.
- Rack (19-inch) and rack unittermThe 19-inch frame that standardizes how equipment mounts - and the rack unit (U), the 1.75-inch height quantum everything is measured in.
- radio propagationtermHow a radio signal actually travels from transmitter to receiver, which depends far more on frequency than on power.
- radio spectrumtermThe range of electromagnetic frequencies used for radio, conventionally divided into bands from VLF to EHF.
- RADIUSacronymThe AAA workhorse: authenticates who connects, authorizes what they get, and accounts for what they used - for ISPs, VPNs, and Wi-Fi alike.
- RAGacronymA technique that feeds an AI model retrieved documents so its answers are grounded.
- RAID is not a backupexpressionThe storage truth that redundancy protects against disk failure, not against deletion, corruption, or ransomware.
- rainbow tabletermA precomputed lookup that reverses unsalted password hashes quickly.
- rate limitingtermCapping how often something may happen, to protect a system from load it cannot absorb.
- RBACacronymRole-Based Access Control: permissions granted to roles, people assigned to roles - access managed by job, not by individual favor.
- read-only FridayexpressionThe ops tradition of making no production changes on Friday, because weekends exist.
- Real Programmers Don't Use PascalloreA 1983 satirical essay whose 'Real Programmer' is a macho hacker who scorns high-level niceties.
- red teamtermA group that plays the adversary to test an organization's defences realistically.
- ReddittermThe threaded, voted discussion platform whose networking and vendor subreddits carry an outsized share of real-world troubleshooting.
- ReDoSacronymA denial-of-service caused by a regular expression that takes catastrophically long on certain input.
- Reflections on Trusting TrustloreKen Thompson's 1984 demonstration that a compiler can hide a self-propagating backdoor invisible in the source.
- regextermA compact pattern language for matching and extracting text.
- region (cloud)termA geographic cluster of availability zones, isolated from every other region - the blast-radius boundary and the data-residency unit.
- regressiontermA defect introduced by a change, where something that previously worked stops working.
- regression testingtermRe-running existing tests to confirm that a change did not break something that already worked.
- remote desktoptermTaking over a user's screen and input from afar - RDP, VNC, and their commercial cousins - support's teleportation.
- remote handsexpressionData-center staff acting as your on-site body: swap the drive, read the LEDs, move the cable - your eyes and hands, billed by the quarter hour.
- repeatertermA radio station on high ground that receives on one frequency and simultaneously retransmits on another, extending the range of low-power stations.
- replay attacktermCapturing a valid message and sending it again to produce an unauthorized effect.
- ResellertermThe company that sells and installs somebody else's products for the organisation that will run them; also called a value-added reseller or integrator.
- reserva de mercadoloreThe Brazilian policy that legally reserved the domestic computer market for nationally-owned companies from 1984 to 1992.
- responsible disclosuretermReporting a vulnerability privately to the vendor and giving them time to fix it before going public.
- RESTacronymAn architectural style for web APIs built on HTTP methods and resources.
- reverse proxytermA server that receives client requests and forwards them to back-end servers on their behalf.
- RFC 1149 (IP over Avian Carriers)loreAn April Fools' RFC from 1990 that specifies carrying IP datagrams by homing pigeon.
- RFC 1918 addressestermThe private IPv4 ranges - 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16 - routable inside, never on the public internet, and the reason NAT exists.
- right to erasuretermThe right to have personal data deleted when there is no longer a lawful reason to keep it - popularly, the right to be forgotten.
- ring topologytermEach node connects to exactly two neighbors, forming a closed loop that traffic travels around.
- RIPacronymRouting Information Protocol - the internet's first common routing protocol: hop count as the metric, 15 hops as the horizon, and 'routing by rumor' as the method.
- RJ45acronymThe eight-position modular connector on the end of nearly every Ethernet patch cord - properly the 8P8C plug.
- RMAacronymReturn Merchandise Authorization: the vendor's blessing to send hardware back - the number without which the box comes home unopened.
- RNGacronymA source of random values, ideally unpredictable.
- RNP (Rede Nacional de Ensino e Pesquisa)acronymBrazil's national education and research network: the academic backbone created in 1989, and the infrastructure the Brazilian internet was actually built on.
- RoadsecloreLatin America's largest hacker festival - a full-day carnival of talks, CTF, drones, and lockpicks that has toured Brazil's state capitals since 2014.
- ROBOTloreA 2017 return of a classic RSA padding oracle affecting many TLS stacks.
- ROCAloreA 2017 flaw in RSA key generation in certain chips that made keys factorable.
- Room 641AloreThe San Francisco AT&T facility where a technician revealed fiber splitters copying Internet traffic for the NSA.
- root causetermThe underlying reason a failure happened, beneath its visible symptoms.
- rough consensus and running codeexpressionThe IETF's working philosophy: standards emerge from broad agreement plus implementations that actually work.
- route table (cloud)termThe per-subnet routing decisions of a VPC: which destinations go to the internet gateway, the NAT, the peering, or the tunnel.
- RowhammerloreA hardware attack that flips memory bits by rapidly accessing neighboring rows.
- RPKIacronymA system of signed records that lets routers check whether a network is allowed to announce a given address block.
- RPMacronymA package format and manager used by Red Hat-family Linux systems.
- RPZacronymA DNS mechanism for rewriting or blocking answers by policy.
- RS256acronymA JWT signing algorithm: RSA with SHA-256.
- RSAacronymThe classic public-key algorithm for signatures and, historically, key transport.
- RSA ConferencetermThe industry's biggest stage: born in 1991 as a small gathering of cryptographers, now the annual San Francisco mega-show where the security business shows what it is selling this year.
- RTFMacronymThe support-culture retort telling an asker the answer is already in the documentation.
- RTMPacronymA protocol for streaming audio and video, historically Flash-based.
- RTSPacronymA control protocol for streaming media - play, pause, seek.
- rubber duck debuggingloreDebugging by explaining your code, line by line, to an inanimate object.
- runbooktermA documented procedure for carrying out a specific operational task or handling a known situation.
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- safe methodtermAn HTTP method whose defined semantics request no state change on the server - reading, not writing.
- safe modetermBooting with minimal drivers and services: if the problem vanishes here, something loaded at startup is the suspect.
- salttermRandom data added to a password before hashing, unique per user.
- SAMLacronymAn XML standard for exchanging authentication between identity providers and services.
- SampaSecloreSao Paulo's CitySec - the informal monthly bar meetup of the city's security professionals and enthusiasts, third Wednesday of the month.
- SANacronymThe certificate field listing all hostnames the certificate is valid for.
- SANS InstitutetermThe best-known commercial training institute in security operations, and home of the GIAC certifications and the Internet Storm Center.
- SAP (Novell)acronymNetWare's Service Advertising Protocol - how servers announced 'here I am, and here's what I offer' across an IPX network.
- SASEacronymGartner's 2019 model that converges the WAN and its security stack into a single cloud-delivered service at the edge, as close to the user as possible.
- SBOMacronymSoftware Bill of Materials: the ingredient list of a piece of software - every component and version, so 'are we affected?' has an answer.
- Schneier's lawexpression'Anyone can invent a security system so clever that he can't think of how to break it.'
- Schrems IIloreThe 2020 EU court ruling that struck down the EU-US Privacy Shield: one Austrian law student's complaints, twice, reshaped transatlantic data law.
- schroedinbugjargonA bug that only manifests after someone reads the code and realizes it should never have worked.
- Schroedinger's backupexpressionThe state of any backup that has never been restored: simultaneously good and bad until someone opens the box.
- SCIMtermSystem for Cross-domain Identity Management: the open standard for provisioning - creating, updating, grouping, and deactivating user accounts across systems over a JSON REST API, with schemas from RFC 7643 and the protocol from RFC 7644.
- Scooter (AltaVista's crawler)loreAltaVista's web crawler, written by Louis Monier at DEC.
- scope creepexpressionThe uncontrolled expansion of a project's scope after it is already underway.
- SCPacronymA simple command for copying files over an SSH connection.
- script kiddiejargonAn attacker who runs other people's exploit tools without understanding how they work.
- SD-WANacronymSoftware-Defined WAN: branch connectivity steered by central policy over any mix of links - MPLS, broadband, LTE - chosen per application in real time.
- SDLCacronymIBM's Synchronous Data Link Control - the link-layer protocol of SNA, and the ancestor of HDLC.
- SDNacronymSoftware-Defined Networking: separating the control plane from the forwarding plane, so the network is programmed centrally instead of configured box by box.
- SEC1acronymA standard format for encoding elliptic-curve private keys.
- secrets managementtermCentralizing passwords, tokens, and keys in a vault with access control, audit, and rotation - instead of scattering them through code and config.
- security grouptermThe cloud's stateful per-instance firewall: allow rules attached to workloads, return traffic implied, default deny inbound.
- security is a process, not a productexpressionBruce Schneier's reminder that security is a process, not a product - nothing you buy makes you done.
- Security LeadersloreThe executive end of the Brazilian security calendar - where the people who sign things meet, rather than the people who configure them.
- security questionstermKnowledge-based authentication - mother's maiden name, first pet - identity proofs from an era before social media published the answers.
- security theaterexpressionBruce Schneier's term for measures that perform protection visibly while providing little of it.
- Segal's lawexpressionA man with a watch knows what time it is; a man with two watches is never sure.
- Segment grouptermA ZPA collection of application segments used as the policy axis: access rules commonly target segment groups, so grouping strategy is policy strategy.
- semantic versioningtermThe MAJOR.MINOR.PATCH convention, where each number carries a promise about compatibility.
- serverlesstermA model where you run code without managing servers, and pay only while it runs.
- service accounttermAn identity for software rather than a person: the credentials under which pipelines, jobs, and applications act.
- service control policytermOrganization-level guardrails that bound what any account may ever do - ceilings on permissions that even administrators cannot exceed.
- service desktermThe single point of contact between users and IT: intake, triage, resolution or escalation, and the record of it all.
- service meshtermA dedicated layer that manages service-to-service communication inside a cluster.
- service providertermThe application side of a federation: the party that consumes assertions or tokens and grants access based on them - SAML's SP, OIDC's relying party.
- Services companytermA company that sells people and process rather than product: consulting, outsourcing, managed operations.
- SEV1jargonThe highest incident severity: the service is down, customers feel it, and everything else can wait.
- severitytermHow bad a fault is, judged by its effect on the business rather than by how loudly it is reported.
- severity levels (P1-P4)termThe impact-and-urgency ladder for incidents: P1 is everyone-down-drop-everything, P4 is a papercut with a queue.
- SFP transceiveracronymSmall Form-factor Pluggable: the swappable module that gives a switch port its physical medium - copper or fiber, short reach or long haul.
- SFTPacronymA file-transfer protocol that runs securely over SSH.
- SHAacronymThe standard family of cryptographic hash functions.
- shadow ITexpressionTechnology and services used inside an organization without the knowledge or approval of central IT.
- shared responsibility modeltermThe cloud's division of labor: the provider secures the infrastructure, the customer secures what they build and configure on it.
- shared VPCtermOne centrally administered network shared into many projects or accounts - the platform team owns the plumbing, product teams deploy into it.
- shelfwarejargonSoftware an organization bought, licensed, and never actually deployed - value sitting on a shelf.
- shellcodetermA small, self-contained piece of machine code an exploit runs, classically to open a shell.
- ShellshockloreA 2014 family of Bash vulnerabilities that let attackers run commands through crafted environment variables.
- Shielded twisted pairtermTwisted-pair cabling with foil or braid shielding - for the environments where twist geometry alone can't fight the noise.
- shift-leftexpressionMoving testing, security, and quality checks earlier in the development process.
- ShmooConloreThe Washington, D.C. hacker convention that stayed small, cheap, and beloved on purpose - held every winter from 2005 until its farewell edition in 2025.
- shoulder surfingjargonStealing information the analog way: reading someone's screen or keyboard over their shoulder.
- SIacronymThe modern metric system of measurement units.
- SID (I-SID)acronymAn identifier that maps a service to a fabric-wide virtual network.
- sidecartermA helper container that runs alongside a main application to add capabilities without changing it.
- SIEMacronymSecurity Information and Event Management: logs from everywhere, correlated into alerts - the security team's central nervous system.
- SIIacronymReusable subscriber-identity data in the certificate issuance process.
- SIKEacronymA post-quantum candidate that was dramatically broken in 2022.
- single pane of glassexpressionThe perennial vendor promise of one dashboard that shows everything - and the engineer's shorthand for doubting it.
- single source of truthexpressionThe principle that each fact should have exactly one authoritative home, with everything else derived from it.
- Single-mode fibertermThe long-haul fiber: a core so narrow light travels one path - distance measured in tens of kilometers, not hundreds of meters.
- SIPacronymThe signaling protocol that sets up voice and video calls.
- SIPRNetacronymThe US Department of Defense network for information classified up to secret, physically separate from both the unclassified network and the public internet.
- SIRTacronymF5's team that handles security incidents and advisories.
- SISBIN (Sistema Brasileiro de Inteligência)acronymThe Brazilian Intelligence System, established in 1999, coordinating intelligence activity across federal bodies with ABIN as its central organ.
- SISCOMIS (Sistema de Comunicações Militares por Satélite)acronymBrazil's military satellite communications system, providing the armed forces with sovereign links independent of commercial or foreign infrastructure.
- six degrees of separationloreThe idea that any two people are connected by a chain of about six acquaintances - and the name of the first social network.
- SLAacronymService Level Agreement: the contract's measurable promises - availability, repair time, throughput - and the penalties when they slip.
- SLAACacronymStateless Address Autoconfiguration: IPv6 hosts build their own addresses from router advertisements - no DHCP server required, no lease table kept.
- SLIPacronymThe Serial Line Internet Protocol - the minimal, pre-PPP way to put IP packets on a serial line.
- SLOacronymA concrete target for how reliable a service should be, like 99.9% of requests succeeding.
- SLOTHloreA 2016 set of attacks abusing obsolete hashes like MD5 in TLS negotiation.
- slow is smooth, smooth is fastexpressionThe special-operations cadence rule: hurrying breeds errors, and errors cost more time than care ever did.
- SMBacronymThe Windows protocol for sharing files, printers, and named pipes.
- smishingtermPhishing carried out over SMS text messages.
- SMTPacronymThe protocol that moves email between mail servers.
- smurf attacktermThe classic amplification DDoS: ICMP echo requests sent to a broadcast address with the victim forged as the source.
- SNAacronymIBM's mainframe networking architecture - the hierarchical world that predated and long coexisted with TCP/IP in the enterprise.
- SNAFUloreWartime slang for a situation that is a mess, yet routinely so.
- SNATacronymRewriting the client source address as traffic passes through a device.
- sneakernetjargonMoving data by physically carrying storage media instead of using a network.
- SNIacronymThe field in a TLS handshake that names which site the client wants.
- SNMPacronymSimple Network Management Protocol: the decades-old standard for polling device health and counters, and for receiving traps when something breaks.
- snowflake serverjargonA server so hand-crafted and unique that nobody could rebuild it from scratch.
- SNRacronymSignal-to-Noise Ratio: how far the signal stands above the noise floor, in dB - the single number that decides whether a link can run its rated speed.
- SNTP (Simple Network Time Protocol)acronymSimple Network Time Protocol: a reduced subset of NTP that speaks the same wire protocol with far less of the algorithm behind it.
- SOAacronymThe DNS record holding a zone's authoritative metadata.
- SOAPacronymAn older, XML-based protocol for structured web-service messages.
- SOARacronymSecurity Orchestration, Automation, and Response: playbooks that act on alerts automatically - enrich, contain, ticket - before a human arrives.
- SOCacronymThe team and facility responsible for continuously monitoring and defending an organization's security.
- SOC 2acronymAn auditing standard that reports on how well a service organization protects customer data.
- social engineeringtermManipulating people, rather than technology, to gain access or information.
- SOLIDacronymThe five object-oriented design principles assembled by Robert C. Martin, arranged into an acronym by Michael Feathers.
- somebody set up us the bombloreAnother garbled line from the same 1991 game's opening as "all your base", now shorthand for a system suddenly and catastrophically compromised.
- SONETacronymSynchronous Optical Network - the telco standard that made optical transport a synchronized hierarchy with 50-millisecond healing rings. SDH is its international twin.
- spaghetti codeexpressionCode whose control flow is so tangled it is nearly impossible to follow.
- Spanning Tree ProtocoltermThe Layer 2 protocol that blocks redundant switch links to prevent loops, keeping exactly one active path between any two points.
- SPBMacronymAn Ethernet fabric technology that builds shortest-path forwarding using IS-IS.
- special category datatermThe data whose misuse cuts deepest - health, biometrics, beliefs, orientation, genetics - locked behind stricter conditions than ordinary personal data.
- SpectreloreA 2018 class of attacks abusing CPU speculative execution to leak memory.
- SPFacronymAn email-authentication method declaring which servers may send for a domain.
- split horizontermA distance-vector routing rule: never advertise a route back out the interface you learned it from.
- split-brainjargonThe cluster failure where partitioned nodes each believe they are the survivor, and both keep writing.
- SPNacronymThe name a Kerberos client uses to request a service ticket.
- SPNEGOtermSimple and Protected GSS-API Negotiation Mechanism: the wrapper that carries a Kerberos service ticket inside HTTP's Negotiate authentication scheme, letting a browser authenticate to a website silently from the user's existing domain session.
- Spring4ShellloreA 2022 remote code execution flaw in the Spring Framework for Java.
- SQLacronymThe standard language for querying and manipulating relational databases.
- SQL injectiontermInjecting database commands through an input that gets concatenated into a query.
- SQL SlammerloreThe 376-byte worm that fit in a single UDP packet and infected most of its 75,000 victims within ten minutes on January 25, 2003.
- SRVacronymA DNS record that advertises the host and port for a specific service.
- SS7acronymSignaling System 7: the signaling network that sets up phone calls and SMS worldwide - designed for a closed club of trusted carriers.
- SSEacronymGartner's 2021 name for the security half of SASE: secure web gateway, CASB, and zero trust network access delivered as one cloud service, with the networking left out.
- SSHacronymThe standard encrypted protocol for remote shell access and secure tunneling.
- SSMAacronymSingle Scan, Multi-Action: the ZIA Service Edge design where content is scanned once and every enabled engine acts on that single pass, instead of daisy-chaining separate inspection devices.
- SSOacronymSingle Sign-On: authenticate once, reach many applications - identity centralized, passwords decimated, and one very important basket for the eggs.
- SSRFacronymServer-Side Request Forgery: tricking a server into making requests on the attacker's behalf - reaching internal addresses the attacker never could directly.
- stack canarytermA known value placed between local buffers and the saved return address, checked before a function returns.
- stack overflowtermExhausting the call stack, usually through recursion that never reaches its base case.
- standard contractual clausestermThe EU's pre-approved contract terms that make personal data transfers to other countries lawful - protection by contract where law alone does not reach.
- standard user vs. adminexpressionDaily work in an unprivileged account, elevation only when needed: the desktop version of least privilege, and malware's least favorite policy.
- Standards bodytermThe laboratories, foundations and specification bodies the commercial entries are built on top of - not companies selling anything, or not only that.
- star topologytermEvery node connects to a central device, and nothing connects directly to anything else.
- stateful firewalltermA firewall that tracks connections, allowing return traffic automatically for sessions it saw begin - judging flows, not lone packets.
- static routetermA route entered by hand rather than learned from a protocol: absolute, silent, and exactly as correct as the person who typed it.
- Statistical multiplexertermA multiplexer that allocates line capacity on demand rather than by fixed time slot.
- storm controltermA per-port ceiling on broadcast, multicast, or unknown-unicast traffic that throttles or shuts the port when a storm begins.
- STPacronymSTP stands for two different things: Spanning Tree Protocol, and Shielded Twisted Pair.
- StratatermPalo Alto Networks' name for its founding network-security family: the next-generation firewalls and everything that manages and subscribes to them.
- stream ciphertermA cipher that generates a keystream and XORs it over the data - any length, no blocks, no padding.
- Sturgeon's lawexpression'Ninety percent of everything is crap.'
- StuxnetloreThe 2010 worm that sabotaged Iranian nuclear centrifuges, the first known cyberweapon to cause physical damage.
- subnettermA slice of a larger network, defined by how many address bits are fixed.
- supernettermA single route that summarizes several smaller networks.
- supply-chain attacktermCompromising software by attacking something it depends on, rather than the target directly.
- support tiers (L1/L2/L3)termThe layered support model: L1 handles volume with scripts and known fixes, L2 brings expertise, L3 is the people who built or own the thing.
- Surrogate IPtermZIA mechanism mapping a known internal IP to an authenticated user for a period, so traffic that cannot carry credentials still gets user-level policy.
- surveillance capitalismjargonThe business model of predicting and steering behavior from harvested personal data - attention in, predictions out, advertisers billed.
- Sweet32loreA 2016 attack exploiting birthday bounds on 64-bit block ciphers like 3DES.
- swivel-chair integrationjargonIntegrating two systems with a human who swivels between screens, reading from one and retyping into the other.
- SYN floodtermA denial-of-service that opens many half-finished TCP connections to exhaust a server's resources.
- syslogtermThe universal log-shipping protocol: devices stream timestamped severity-tagged events to a central collector, from debug chatter to emergencies.
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- "the padlock means the site is safe"loreDisputed / commonly mistoldThe padlock proves the connection is encrypted to whoever holds that domain - it says nothing about who they are. Phishing sites get certificates in minutes, for free.
- "there is no cloud, it's just someone else's computer"loreDisputed / commonly mistoldThe sticker-slogan half-truth: physically accurate, architecturally misleading. The cloud's substance is elasticity, APIs, managed services, and global footprint - properties no single computer has.
- "Tor is only for criminals"loreDisputed / commonly mistoldTor's daily users are overwhelmingly ordinary: people evading censorship, journalists protecting sources, researchers, and the privacy-minded - the network was funded to protect exactly them.
- T1acronymThe North American 1.544 Mb/s digital carrier - 24 channels of 64 kb/s, the DS1, the leased line a generation of WANs was built from.
- T568A / T568BtermThe two TIA-568 pinouts for terminating twisted pair on RJ45 - identical performance, different wire-to-pin order.
- TACacronymThe vendor's technical assistance centre: the engineers you reach when a product itself, rather than your configuration of it, may be at fault.
- TAIacronymA continuous atomic timescale with no leap seconds.
- tarpitjargonA defensive trick that answers attackers extremely slowly, wasting their time instead of refusing them.
- TCP three-way handshaketermThe three-message exchange that opens a TCP connection: SYN, SYN-ACK, ACK.
- TCP/IPloreThe two-protocol architecture, split from a single design in the late 1970s, that became the common language of the internet.
- technical debtexpressionThe future cost of choosing a quick solution now over a better one later.
- TELEBRÁSloreTelecomunicações Brasileiras S.A.: the state holding that organized Brazil's telecom operators from 1972; the whole system - three fixed holdings, Embratel, and eight cellular holdings - was privatized in twelve auctions on 29 July 1998, the largest privatization in Brazilian history.
- TELESPloreTelecomunicações de São Paulo: the Telebrás system's São Paulo fixed-line operator (1973-1998), successor to the CTB's São Paulo operations; acquired by Spain's Telefónica in the 1998 privatization, becoming Telefônica Brasil (the Vivo brand from 2012). Under Telefónica it launched São Paulo's ADSL broadband, Speedy, in 1999.
- TELNETacronymAn old, unencrypted remote-terminal protocol, superseded by SSH.
- TerrapinloreA 2023 attack that can weaken or truncate the SSH handshake.
- test automationtermLetting machines execute tests, so they run on every change instead of when someone has time.
- testing in productionexpressionThe practice - reckless or disciplined, depending entirely on tooling - of validating changes on the live system.
- TFTPacronymA minimal file-transfer protocol with no authentication, used for booting devices.
- the 'room 404' mythloreDisputed / commonly mistoldThe popular but false claim that HTTP 404 is named after a specific room at CERN where the web's first server lived.
- the 3-2-1 backup ruleexpressionThe backup rule of thumb: three copies of the data, on two different media, with one copy off-site.
- the 414sloreA group of Milwaukee teenagers who broke into dozens of computer systems in 1983 and put hacking on front pages.
- the 500-mile emailloreA classic sysadmin tale of an email system that mysteriously could not send mail farther than about 500 miles.
- the 640K quoteloreDisputed / commonly mistoldThe famous line '640K ought to be enough for anybody', attributed to Bill Gates, who has repeatedly denied ever saying it.
- the Blaster wormloreThe August 2003 Windows worm that rebooted PCs worldwide and carried a taunt addressed to Bill Gates.
- the CAP theoremtermA distributed system facing a network partition must choose between consistency and availability; it cannot keep both.
- The Cathedral and the BazaarloreEric Raymond's 1997 essay contrasting closed, top-down development with open, community-driven development.
- the cobra effectexpressionAn incentive that worsens the problem it was meant to solve, named for a colonial bounty on cobras that created cobra farms.
- the Crypto WarsloreThe 1990s battle over whether strong cryptography could be exported, escrowed, or used freely at all.
- the Cuckoo's EggloreCliff Stoll's 1986 hunt for a hacker that began with a 75-cent accounting error.
- the DAO hackloreThe 2016 drain of the largest crowdfunded smart contract, answered by the hard fork that split Ethereum in two.
- the demo godsexpressionThe capricious deities who decide whether a live demo works - having behaved perfectly in every rehearsal.
- the ENIAC programmersloreThe six women who programmed the ENIAC in the 1940s, largely uncredited for decades.
- the ether / aetherloreThe imaginary medium light was once thought to travel through, and the wink in the name Ethernet.
- the evil bitloreThe April Fools' RFC proposing that malicious packets simply set a header bit to declare themselves evil.
- the Fail WhaleloreTwitter's overload mascot, a whale lifted by birds, that turned chronic downtime into a beloved brand from 2007 to 2013.
- the fallacies of distributed computingexpressionThe eight assumptions every distributed-systems novice makes, starting with 'the network is reliable', catalogued at Sun in the 1990s.
- the first .com domainloresymbolics.com, registered on March 15, 1985 by a Lisp machine maker, was the Internet's first .com.
- the first banner adloreAT&T's 'Have you ever clicked your mouse right here? You will.' on HotWired, October 27, 1994 - the ad that founded the web's business model.
- the first emailloreRay Tomlinson sent the first networked electronic mail between two ARPANET machines in 1971, choosing @ to separate user from host.
- the first spam emailloreA 1978 DEC marketing message blasted to hundreds of ARPANET users, generally cited as the first spam.
- the first tweetloreJack Dorsey's 2006 message 'just setting up my twttr', the first post on Twitter.
- the first web pageloreThe plain page Tim Berners-Lee published at CERN in 1991 to explain the World Wide Web itself.
- the GNU ManifestoloreRichard Stallman's 1985 call to build a free Unix-compatible operating system that anyone could share and change.
- the golden hammerexpressionOver-relying on one familiar tool for every problem, whether or not it fits.
- the Green Card spamloreThe April 1994 Usenet mass-posting by two immigration lawyers that made commercial spam a household problem.
- the Hacker ManifestoloreA short 1986 essay, written after its author's arrest, that became the defining statement of hacker curiosity.
- the happy pathexpressionThe default scenario where everything is valid and nothing goes wrong.
- the Homebrew Computer ClubloreThe 1975 Menlo Park hobbyist club where the personal computer industry, and its first fight over software, began.
- the ILOVEYOU virusloreThe 2000 email worm whose 'ILOVEYOU' subject line tricked millions into infecting their own machines.
- the IOCCCloreThe contest, running since 1984, that celebrates the most gloriously unreadable working C programs on Earth.
- the Jargon FileloreThe long-running community dictionary of hacker slang and culture, maintained since the 1970s.
- the Knight Capital glitchloreThe 2012 trading firm that lost about 440 million dollars in 45 minutes from a botched software deployment.
- the Konami CodeloreThe button sequence up up down down left right left right B A, a cheat that became a cultural in-joke.
- the L0pht testimonyloreThe 1998 Senate hearing where seven hackers testified they could take down the Internet in thirty minutes.
- the lawsuit that created ZIPloreThe 1988 lawsuit that was meant to protect the ARC format, and instead produced ZIP.
- the leap secondloreThe extra second occasionally inserted to keep atomic time aligned with Earth's rotation, and the outages it caused.
- the map is not the territoryexpressionKorzybski's warning that representations are not the reality they describe - and confusing them has consequences.
- the Mars Climate OrbiterloreThe 1999 Mars probe lost because one team's software spoke pound-force seconds and the other expected newton seconds.
- the Max Headroom incidentloreThe 1987 Chicago broadcast hijacking by someone in a Max Headroom mask, still unsolved.
- the Melissa virusloreThe March 1999 Word-macro virus that mailed itself to the first 50 Outlook contacts and buried corporate email worldwide.
- the Morris WormloreThe 1988 self-replicating program that became the first worm to disrupt the early internet at scale.
- the Mother of All DemosloreDouglas Engelbart's 1968 demonstration that unveiled the mouse, hypertext, and live collaboration at once.
- the Net routes around damageexpressionJohn Gilmore's line that the Net treats blockage as a fault to route around - resilience as a design temperament.
- the ninety-ninety ruleexpression'The first 90 percent of the code accounts for the first 90 percent of the development time. The remaining 10 percent accounts for the other 90 percent.'
- the north star metricexpressionThe single measure a team agrees best captures the value it delivers, used to align everyone's work.
- the only secure computer is powered offexpressionGene Spafford's reductio: the only truly secure computer is off, encased in concrete, guarded - and useless.
- the Pentium FDIV bugloreA 1994 flaw in the Intel Pentium that returned slightly wrong answers for certain floating-point divisions.
- the Peter principleexpressionIn a hierarchy, people rise to their level of incompetence.
- the principle of least astonishmentexpressionA component should behave the way most users will expect it to behave; surprise is a defect.
- the S in IoT stands for securityexpressionThe joke that the S in IoT stands for security - there is no S, and too often no security either.
- the second-system effectexpressionFred Brooks's warning that the successor to a successful system tends to be overengineered with every idea saved up from the first.
- the Silk RoadloreThe Tor-hidden marketplace, 2011 to 2013, whose rise and takedown defined the public's picture of the dark web.
- the Slashdot effectloreThe crash of a small website under the traffic of a sudden front-page link, named for the site that did it nightly.
- the Story of MelloreA 1983 Usenet poem about Mel Kaye, a programmer who wrote code so close to the machine it defied the idea of ever rewriting it.
- the street finds its own uses for thingsexpressionWilliam Gibson's observation that technology's real uses are invented by its users, not its designers.
- the Streisand effectloreWhen an attempt to hide or suppress information ends up drawing far more attention to it.
- the Swiss cheese modelexpressionJames Reason's accident model: every defense layer has holes, and disasters happen when the holes line up.
- the Trojan Room coffee potloreThe Cambridge coffee machine whose monitoring camera became the world's first webcam.
- the Turing testloreAlan Turing's 1950 proposal to judge machine intelligence by whether it can converse indistinguishably from a human.
- the Two Generals problemtermThe proof that two parties on an unreliable channel can never be certain they agree to act together.
- the two hard thingsexpression'There are only two hard things in Computer Science: cache invalidation and naming things.'
- the two-pizza teamexpressionThe rule that a team should be small enough to feed with two pizzas.
- the wall of confusionexpressionThe dysfunction where developers and operations hand work back and forth without shared ownership.
- the weakest linkexpressionThe chain proverb applied to security: the system's real strength is its most neglected component, not its best one.
- the WinRAR licenceloreWinRAR's forty-day trial has never stopped working, on any version, for about thirty years - which turns out to be a business model rather than an oversight.
- the XY problemexpressionAsking for help with your attempted solution (Y) instead of your actual problem (X) - and burning everyone's time on the wrong question.
- the Year 2038 problemtermSigned 32-bit Unix time overflows at 03:14:07 UTC on 19 January 2038, wrapping the clock to December 1901. Unlike Y2K it is a hard representational limit, not a formatting convention, and it cannot be patched around without widening the field.
- the zero-one-infinity ruleexpressionAllow none of a thing, one of a thing, or any number of a thing; every other limit is arbitrary.
- Therac-25loreThe radiation-therapy machine whose software race conditions delivered massive overdoses in the 1980s, the founding case study of software safety.
- there are no solutions, only trade-offsexpressionThomas Sowell's economics dictum, adopted whole by engineering: every choice purchases its benefits with costs elsewhere.
- threat modeltermA structured look at what could go wrong, who might attack, and what is worth defending.
- thundering herdjargonWhat happens when a crowd of clients all wake up, retry, or reconnect at exactly the same moment.
- tickettermThe unit of support work: one tracked record per issue, with status, owner, history, and priority - if it is not in the ticket, it did not happen.
- ticket ping-pongjargonA ticket bounced between teams, each reassigning it as not-mine - the organizational failure mode where routing replaces resolving.
- tiger teamjargonA small, hand-picked group pulled out of normal structure to attack one hard problem until it yields.
- TL;DRacronymToo long; didn't read: the complaint that became the standard label for a summary.
- TLDacronymThe last label of a domain name, like com or org.
- TLSacronymThe protocol that encrypts and authenticates most internet traffic, the S in HTTPS.
- toiljargonRepetitive, manual operational work that scales with the service but adds no lasting value.
- Token RingtermThe deterministic LAN technology (IEEE 802.5) where a circulating token grants the right to transmit, championed by IBM against Ethernet.
- tokenizationtermReplacing sensitive values with meaningless stand-ins, keeping the real data in one guarded vault - the token is useless anywhere else.
- top talkersjargonThe hosts, flows, or applications consuming the most bandwidth on a link - the first list every traffic tool shows.
- TortermAn anonymity network that routes traffic through three volunteer relays, each peeling one layer of encryption, so no single relay knows both ends.
- Tor relaytermOne of the volunteer-run servers that forward Tor traffic.
- TOTPacronymA one-time code that changes every 30 seconds, used for two-factor auth.
- TPSacronymA throughput measure counting transactions handled each second.
- TR-069termThe Broadband Forum's remote-management protocol: the ISP's ACS can configure, update, and diagnose the CPE fleet without a single site visit.
- tracking pixeltermAn invisible one-pixel image or beacon whose loading reports that you opened the page or email - presence-tracking disguised as content.
- Training organisationtermThe companies and bodies that decide what competence looks like in a technology and who may claim it.
- Transceiver (pluggable optics)termThe pluggable module that gives a switch port its personality - copper or fiber, short reach or long, one lineage from GBIC to OSFP.
- transformertermThe 2017 neural-network design that made modern language models practical, built on self-attention.
- transit gatewaytermThe cloud's central router: VPCs, VPNs, and interconnects attach to one hub instead of meshing with each other.
- tree topologytermA hierarchy of stars: a root branching into layers, with no loops in the intended design.
- triagetermSorting incoming problems by severity and routing them, so that the queue reflects impact rather than arrival order.
- tribal knowledgejargonThe critical operational knowledge that lives only in certain people's heads, never in the documentation.
- TROOPERSloreERNW's Heidelberg conference - the one experienced European practitioners name when they can only pick one: trainings, three tracks, and roundtables where speakers and attendees argue as equals.
- truck rollexpressionDispatching a technician to the premises - the most expensive way to close a ticket, and sometimes the only one.
- trunk porttermA switch port carrying multiple VLANs at once, each frame tagged with its VLAN ID so the far end can sort them back out.
- trust, but verifyexpressionThe old proverb of cooperative suspicion - accept the claim, then check it anyway.
- Trusted networktermA ZCC-detected network condition defined by admin criteria - preferably the static DNS servers and search domains over dynamic hostname resolution.
- TSIGacronymA shared-key method for authenticating DNS transactions like zone transfers.
- TTLacronymA counter that limits how long data lives or how far a packet may travel before being discarded.
- TTPacronymTactics, techniques, and procedures: the layered description of how a threat actor operates.
- turtles all the way downexpressionThe recursion joke applied to trust: every layer rests on another layer, and eventually you must simply stand somewhere.
- two is one, one is noneexpressionThe redundancy proverb: with two you can lose one; with one, a single failure leaves you with nothing.
- TXTacronymA general-purpose DNS record holding free-form text.
10
- UDPtermThe minimal transport that wraps a packet with just ports and a checksum and sends it with no handshake, no ordering, and no retransmission: fire and forget.
- ULIDacronymA sortable, unique identifier alternative to UUID.
- underlay / overlayexpressionThe two-layer view of modern networks: the underlay is the physical routed plumbing; the overlay is the virtual topology tunneled on top of it.
- UNICAMPloreUniversidade Estadual de Campinas: the Campinas state research university, a founding ANSP participant alongside USP and UNESP in the pre-internet academic networking that became Brazil's on-ramp.
- unicasttermCommunication addressed to exactly one recipient.
- upstream / downstreamexpressionThe two directions of an access link: downstream toward the subscriber, upstream toward the internet - historically sized very unequally.
- use-after-freetermUsing a pointer to memory that has already been released, back when it still meant something.
- USPloreUniversidade de São Paulo: Brazil's largest research university and a founding participant of the ANSP academic network - Brazilian internet history runs through its physics and engineering departments' need to reach colleagues abroad.
- UTCacronymThe primary civil time standard the world sets clocks by.
- UTPacronymUnshielded twisted pair - the copper cabling that carries almost every wired office connection.
15
- vaporwarejargonA product announced with fanfare that never ships - or ships so late and so diminished that the announcement was the product.
- VendortermThe company that makes the product, as distinct from anybody who sells, installs or operates it.
- VHF / UHFacronymVery high frequency (30 to 300 MHz) and ultra high frequency (300 MHz to 3 GHz): the line-of-sight bands.
- vi / VimtermThe modal terminal editor that is on essentially every Unix-like system, and its dominant modern successor Vim.
- VIPacronymThe address clients connect to on a load balancer.
- virtual appliancetermA vendor's network function shipped as a VM image - the firewall or load balancer you rack by launching instead of lifting.
- VLANacronymVirtual LAN: a logical Layer 2 broadcast domain carved out of a physical switch network, isolating traffic without separate hardware.
- VLC (VideoLAN Client)termThe VideoLAN Client: a free, open-source media player that began in 1996 as a student project to stream video across a French university's campus network, and became one of the most widely installed pieces of software ever written.
- VLSMacronymUsing different subnet sizes within the same network, sized to each segment's need.
- VPCacronymVirtual Private Cloud: your own logically isolated network inside a public cloud - address space, subnets, routing, and gateways, defined in software.
- VPC peeringtermA private one-to-one link between two VPCs, routing their address spaces to each other - non-transitive by design.
- VPNacronymAn encrypted tunnel that carries your traffic as if you were on another network.
- VRFacronymVirtual Routing and Forwarding: multiple independent routing tables on one router, so overlapping or unrelated networks never mix.
- VRRP / HSRPacronymThe first-hop redundancy family - VRRP (the open standard) and Cisco's HSRP: two or more routers share one virtual gateway IP and MAC, so the default gateway survives a device failure.
- VXLANacronymVirtual Extensible LAN: stretches Layer 2 segments over a routed Layer 3 network by encapsulating frames in UDP, with 16 million segment IDs.
24
- WADacronymThe FortiGate process that handles proxy-based inspection.
- WAFacronymA filter that inspects web traffic and blocks application-layer attacks.
- walled gardenexpressionA restricted network state where the subscriber can reach only the provider's portal - used for unpaid bills, activation, or infected hosts.
- WannaCryloreThe 2017 ransomware worm that spread through a leaked Windows exploit and crippled systems worldwide.
- war roomjargonThe room, physical or virtual, where an incident's responders gather until the thing is fixed.
- warm boot / cold bootexpressionRestarting without cutting power versus from full power-off - the cold boot clears states the warm one preserves.
- WCCPacronymA protocol for transparently redirecting traffic to a cache or proxy.
- wetwarejargonThe humans in the system, named as if they were another component alongside hardware and software.
- Wheeler's aphorismexpression'All problems in computer science can be solved by another level of indirection', with the folk corollary: except too many levels of indirection.
- white / black / grey hatjargonA shorthand for a hacker's intent: white hat (authorized/defensive), black hat (malicious), grey hat (in between).
- Wi-FitermThe consumer name for wireless LAN built on IEEE 802.11 - and a certification mark from the Wi-Fi Alliance.
- Wi-Fi site surveytermMeasuring actual coverage, interference, and neighbor networks on site before or after placing access points - the map versus the guess.
- wire speedexpressionForwarding at the full rate of the medium with no queueing loss - the benchmark claim every datasheet makes and every RFC 2544 test verifies.
- Wiring closettermThe telecom room where a floor's cabling terminates - patch panels, switches, and the boundary between horizontal and backbone cabling.
- Wirth's lawexpressionSoftware is getting slower more rapidly than hardware is getting faster.
- wizardjargonA person with deep, almost intuitive mastery of a system.
- workaroundtermA change that restores function without addressing why it broke, and which therefore continues until somebody actively ends it.
- workload identitytermWorkloads proving who they are through the platform itself - short-lived, automatically issued credentials instead of long-lived secrets in files.
- works on my machineexpressionThe developer's classic defense when code fails everywhere except their own laptop.
- worse is betterexpressionThe observation that a simpler, less complete design often wins over a more correct but complex one.
- WPAacronymThe Wi-Fi Alliance's security scheme for wireless LANs - WPA2 and WPA3 today, replacing the broken WEP.
- WPADacronymA method for browsers to find a PAC file automatically.
- WSacronymA protocol for full-duplex, persistent connections between a browser and server.
- WSSacronymWebSocket encrypted with TLS.
7
- X.21acronymITU-T's interface for circuit-switched data networks - the serial physical-layer standard that often sat beneath X.25.
- X.25acronymThe first widely deployed packet-switching standard - ITU-T's 1976 protocol that ran WANs, ATMs, and card networks for decades.
- XDRacronymExtended Detection and Response: EDR's scope widened - endpoint, identity, email, network, and cloud signals correlated in one detection fabric.
- Xerox PARCloreThe Palo Alto research lab that invented the modern computer's furniture, and famously let others sell it.
- XNSacronymXerox's late-1970s protocol architecture - the ancestral design that Novell IPX, and much else, copied.
- XSSacronymAn attack that injects malicious script into a web page so it runs in other users' browsers.
- XXEacronymAn attack that abuses XML external entities to read files or reach internal systems.
7
- Y2KloreThe two-digit-year defect that threatened date logic worldwide at the 1999 to 2000 rollover, and the remediation effort that largely defused it.
- YAGNIexpressionThe principle that you should not build functionality until it is actually required.
- yak shavingloreThe chain of unrelated sub-tasks you must finish before you can do the thing you actually set out to do.
- YAMLacronymA human-readable data format often used for configuration.
- you build it, you run itexpressionThe DevOps principle that the team that writes a service also operates it in production.
- you can't secure what you can't seeexpressionThe visibility maxim: security begins with an accurate inventory of what exists, because unknown assets get no controls.
- YSTSloreYou Shot the Sheriff: Brazil's curated, single-day security conference - invitation-flavored, bar-hosted, and famously well-connected.
12
- Z-TunneltermClient Connector's transport to a Service Edge: 1.0 is an HTTP CONNECT tunnel shaped for web; 2.0 speaks TLS/DTLS and carries all ports and protocols.
- Zawinski's lawexpressionEvery program attempts to expand until it can read mail; those which cannot are replaced by ones which can.
- ZCCacronymZscaler Client Connector: the endpoint agent that authenticates the user, classifies the network state, and forwards traffic per its forwarding profile.
- ZDXacronymZscaler Digital Experience: endpoint-to-application experience monitoring riding the same vantage points as the brokered data path.
- zero trusttermA security model that trusts nothing by default and verifies every request, wherever it comes from.
- Zero Trust ExchangetermZscaler's globally distributed proxy platform: every connection terminates at a Service Edge, is identified and inspected, then completed onward - sources connect to the Exchange, the Exchange connects to destinations.
- zero-daytermA vulnerability unknown to the vendor, with zero days available to have patched it.
- ZerologonloreA 2020 flaw letting attackers take over a Windows domain controller.
- ZIAacronymZscaler Internet Access: the Exchange's outbound seat - secure web gateway, cloud firewall, and data protection applied between users and the internet/SaaS.
- ZIdentitytermZscaler's unified identity layer for the Zero Trust Exchange: one place to integrate identity providers and manage admin and user identity across the platform's services.
- ZPAacronymZscaler Private Access: per-application, per-session brokered access to private apps - user and App Connector both dial out, a Service Edge stitches the Microtunnels.
- ZTNAacronymZero Trust Network Access: per-application access granted after verifying user, device, and context - no network-wide tunnel, no flat inside.
10
- :-) (the first emoticon)loreThe sideways smiley proposed on a CMU bulletin board in 1982 to mark jokes in plain text.
- "5 GHz Wi-Fi is always better"loreDisputed / commonly mistoldHigher bands carry more data but die faster through walls and distance. 5 GHz wins next to the router; 2.4 GHz often wins two rooms away - it is physics, not quality tiers.
- @ (the at sign in email)loreRay Tomlinson's 1971 choice of @ to separate a user from their host in networked email.
- 2600 MagazineloreThe Hacker Quarterly: the printed voice of hacker culture since 1984, and the origin of the HOPE conference and the Friday 2600 meetings.
- 418 I'm a teapotloreAn April Fools' HTTP status code, defined in 1998, returned by a teapot asked to brew coffee.
- 42 (the Answer)loreThe number a supercomputer gives, after 7.5 million years, as the Answer to Life, the Universe, and Everything.
- 8.8loreChile's technical hacking conference - '100% técnico y académico', wrapped every year in a different pop-culture theme, from The Matrix to Unreal.
- 802.1QacronymThe IEEE standard that adds a VLAN tag to an Ethernet frame - the reason one physical link can carry many virtual LANs.
- 802.1XacronymPort-based network access control - the IEEE standard that makes a switch port or access point authenticate before it forwards traffic.
- 802.3acronymThe IEEE working group and standard for Ethernet - every wired speed and medium, plus Power over Ethernet.