fail2ban

Installation
SKILL.md

Identity

  • Unit: fail2ban.service
  • Config: /etc/fail2ban/jail.local (local overrides — never edit jail.conf)
  • Jails dir: /etc/fail2ban/jail.d/ (drop-in jail files)
  • Filters dir: /etc/fail2ban/filter.d/ (regex patterns per service)
  • Actions dir: /etc/fail2ban/action.d/ (ban/unban actions)
  • Logs: journalctl -u fail2ban, /var/log/fail2ban.log
  • Install: apt install fail2ban / dnf install fail2ban

Key Operations

Goal Command
Check status (all jails) sudo fail2ban-client status
Status of specific jail sudo fail2ban-client status sshd
Unban an IP sudo fail2ban-client set sshd unbanip 1.2.3.4
Manually ban an IP sudo fail2ban-client set sshd banip 1.2.3.4
Test a filter sudo fail2ban-regex /var/log/auth.log /etc/fail2ban/filter.d/sshd.conf
Reload config sudo fail2ban-client reload
Related skills
Installs
1
GitHub Stars
5
First Seen
Mar 18, 2026