Skill · Linux · Secure a Linux system
Filter a server's traffic with a host firewall, NAT included
Filter a server's traffic with its host firewall (UFW, firewalld or nftables) without losing the SSH session, make rules persist across reboots, and expose a service through NAT or port forwarding. The stateful firewall model belongs to network.firewall.filter.
Start lesson 1The Linux domain
- 6 lessons
- ~4 h 15 of reading
- 5 quizzes
- 0 proof lab
The path
Where it comes from, where it leads
What you need to know first, where you stand on this skill, and what it opens next. Your status is computed in your browser, from what you have read and passed.
Before · 1 prerequisite
This skill, for you
Filter a server's traffic with a host firewall, NAT included
Computing
It unlocks · nothing yet
No other skill requires it: it is an end-of-path skill.
The path through the foundations From the most upstream foundation to this skill: what is in place, what remains to read.
Lessons
How to learn it
6 lessons, about ~4 h 15, in program order. Each lesson ends with its quiz.
The program
6 lessons · ~4 h 15
Beyond the lessons
Assess, practise, pass the proof
Reading a lesson confirms nothing. A skill is confirmed by a passed quiz, practised in a guided lab, and put to the test by a challenge or a mission; an imported lab result is not verified by the site.
Assess yourself
5 quizzes
At the end of the lessons: passed at 70%, they confirm the skill.
Practice
3 guided labs
Proof
No proof
A practical proof is a challenge, a capstone or a declared lab.
Used by the mission “Put a server into production”, which has its proof.
Placement test
Preparing the questions…
Your answers in detail
For each question asked: your answer, the correct answer, its explanation and the page to reread.
Around it
Who requires it, who teaches it
Required by
- Linux Administrator
- Cloud Engineer
- LFCS
- RHCSA (EX200, RHEL 10)
In red: the certification it prepares for.
Taught by
Same block · Secure a Linux system