Byggt av en yrkesperson, med integritet i första rummet
Verktygslådan för nätverk och säkerhet som håller dina data på din maskin.
Subnätsberäkningar, DNS- och e-postdiagnostik, certifikatsinspektion och mycket mer, beräknat lokalt i din webbläsare. Ingen uppladdning, ingen loggning, inget konto behövs för de dagliga verktygen.
Tillgängliga nu
Byggt av någon som har gjort jobbet sedan 1996.
Trettio år inom företagsnätverk och säkerhet, levererat av en aktiv instruktör och inte av en marknadsföringssida. Certifierad på plattformar, så att jämförelserna här görs ärligt, inte för att sälja.
The chapters lived from inside
In every one of these, employer or vendor, the work was the same shape: facing the end customer, in pre-sales and in post-sales technical support, and very often acting as the technical proxy and enablement facilitator for the partners who had to carry the product themselves. The job was to leave the customer with something that worked better than it did before — an innovation, a solution, an improvement they could keep running after I left. The full telling lives at the career record.
- Cabletron och Enterasys1996 – 2007
- Riverstone Networks2000 – 2002
- Cisco Systems2003 – 2008
- IronPort Systems2004 – 2005
- NetScreen och Juniper2009 – 2014
- Extreme Networks2013 – 2014
- FireEye, McAfee and Ixia2015 – 2019
- Pulse Secure2018 – 2019
- Palo Alto Networks2013 – 2015
- F52015 – present
- Fortinet2022 – present
- Netskope2024 – present
- Ping Identity and ForgeRock2025 – present
- Zscaler2026 – present
- Check Point2026 – present
Plattformarna, undervisade och hållna aktuella.
What is here
Vendor hubs →
One door per platform: the tools, articles and certification material for that vendor, gathered in one place.
Tools →
Deterministic calculators and explainers for networks, security and identity. They compute in your browser and send nothing anywhere.
152 live
Learn →
Technical articles on the protocols and products behind the tools, written to be read rather than skimmed.
553 articles
Glossary →
Every term and acronym used across this site, defined once and cross-referenced. The thing to open mid-article.
Industry →
Company histories from the beginning of networking to now, including the ones that failed and the ones nobody remembers.
289 companies4 of them turn 50 this year
The Practice →
How the work is actually done rather than how the technology works. Triage, escalation, evidence, handover.
64 published
Certification guides →
What each exam tests and what to study for it. Free, and useful whether or not you ever book a course.
105 guides
Study guides →
Objective-by-objective walkthroughs for the exams, showing what is covered here and, honestly, what is not.
Training I teach →
Authorized instructor-led courses across four platforms, delivered through Red Education.
Advisory →
Independent judgement on decisions that have not been made yet. Scoped work, written answer, no on-call.
By engagement
About →
Who is writing all of this, what I have done, and why any of it should be trusted.
The career record →
Fifteen chapters from 1996 onward, each told from inside the company it happened in.
Red Education →
The global authorized training centre my courses are delivered through, and the story of how it got there.
Varför lokal körning spelar roll i säkerhetsarbete.
När du klistrar in en konfiguration, en paketinspelning eller ett certifikat i ett verktyg innehåller de uppgifterna ofta hemligheter. Här körs de dagliga verktygen helt i din webbläsare. Indata lämnar aldrig din enhet, så det finns inget att logga, läcka eller begära ut.
Prova ett verktyg nu.
CIDR-kalkylatorn nedan körs lokalt. Ange ett nät och ett prefix för att se adressintervallet, antalet värdar och masken. Ingenting skickas någonstans.
CIDR-kalkylator
Analyserar ett enskilt IPv4-CIDR-block: nät, broadcast, mask och värdintervall.
Körs lokalt, ingenting skickas till någon server.