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Linux Security
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Short lesson
Pipelines in one minute · 8 min
Combine small tools: grep filters lines, awk/cut pick fields, sort | uniq -c counts, xargs turns lines into arguments. Read logs with journalctl -u UNIT.
L3Harden a fresh serverterminal
Harden this server: disable SSH password authentication and root login, install and enable fail2ban, and enable the firewall allowing only SSH.
Sign up to practiseL4Suspicious persistenceterminal
An attacker added a backdoor. Find the malicious cron entry for root that downloads and runs a script, remove only that entry, and lock the unauthorised account they created. Enter the account name as your answer.
Sign up to practiseL5Incident summarytext
Write a short incident summary (max 120 words) of the backdoor you found: what happened, impact, actions taken, follow-ups.
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