Train
Training
Authorized instructor-led courses across four platforms, built on decades of engineering practice.
F5 · Fortinet · Extreme Networks · Netskope
Courses, schedules and what to expectByggt av en yrkesperson, med integritet i första rummet
A network and security workbench built from thirty years inside the field
Tools you can use, explanations you can learn from, the companies and people that built the industry, and professional training and advisory when the problem leaves the browser.
Network and security, from the packet to the people behind it.
Ctrl K
Try:
Tillgängliga nu
Start here
- I need to calculate or inspect somethingTools compute
- I want to understand how something worksLearn read
- I am tracing a company, a product or a storyIndustry trace
- I need to train myself or a teamTraining train
- I have a consequential decision to makeAdvisory decide
- I don't know yet. Show me something interestingTake me somewhere wander
Try something now
Type a block and read the answer as you type. The full calculator, with subnetting, VLSM and overlap checks, is one click away.
- Network
- 192.168.1.0
- Broadcast
- 192.168.1.255
- Usable range
- 192.168.1.1 – 192.168.1.254
- Usable hosts
- 254
- Special-purpose ranges (IANA)
- Private-Use, 192.168.0.0/16 (RFC 1918)See the ranges in the full calculator
Computed in your browser. Nothing was uploaded, nothing was logged. How privacy works here
Browse by platform
One door per vendor: the tools, articles and certification material for that platform, with its reading path and industry record where they exist, gathered in one place.
What's happening
New
- New toolNew tool: the routing table explainer reads ip route, netstat -rn and route print2026-10-19
- New articleThe four new articles join their series, and every article they cite now cites them back2026-10-19
- ImprovedThe translators' guide is now on the contribute page, and every language keeps its own punctuation2026-10-19
Take me somewhere
One random door into the whole corpus: a company with a story, an odd tool, a term nobody says out loud, a person who changed the field, a career to explore.
The oldest ancestor here dates from 2004: the bits-and-bytes calculator, rebuilt · the 2004 site itself, navigable · the earlier sites
Work with me
When the problem leaves the browser. Three ways, each with its own page and its own terms.
Decide
Advisory
Executive technical judgement on a technology decision before it is made: scoped work, a written answer you can defend internally, no on-call.
How an engagement worksListen
Speaking
Talks for conferences, company events and team gatherings, on the technology and on the people who work with it.
Talks, formats and bookingWhy trust this
- Local-firstThe catalogue's tools compute in your browser: no upload, no logging, no account. The red room's few live lookups name the service they ask, and send nothing until you press Ask.
- Sourced, with datesTechnical claims cite vendor documentation and standards, each with the date it was read.
- Open sourceThe whole site is a public repository. Read the code behind any result.
- A named authorOne person, thirty years in the field, with a career record you can check.
Built and maintained by Rodolfo Nützmann, a network and security engineer and instructor since 1996.