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terminalskills/skills

fail2ban

>- Protect servers from brute force attacks with Fail2Ban. Use when a user asks to block repeated failed login attempts, protect SSH, secure web servers from brute force, or ban malicious IPs automatically.

First seen Aug 14, 2026

Installation

$ npx skills add terminalskills/skills --skill fail2ban
View on skills.sh ↗ GitHub repository ↗

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More details

Agent compatibility

Declared targets from SKILL.md / docs. Unmarked agents are not listed — the skill may still install via the CLI.

Claude Code Not declared
Cursor Not declared
Codex Not declared
GitHub Copilot Not declared
Windsurf Not declared
Gemini CLI Not declared
Cline Not declared
OpenCode Not declared

Repository health

Stars 146
License LICENSE
Default branch main
Open issues 1
Status Active

Skill metadata

Parsed from SKILL.md frontmatter.

Version1.0.0
LicenseApache-2.0
CompatibilityLinux
More metadata
author
terminal-skills
version
1.0.0
category
devops
tags
["fail2ban","brute-force","ssh","security","firewall"]

Package contents

Files included with this skill beyond the listing page.

  • skill md SKILL.md 1,733 B
  • docs SUMMARY.md 219 B

History

  1. First seen on skills.sh
  2. First recorded snapshot · 3 installs

SKILL.md

Fail2Ban

Overview

Fail2Ban monitors log files for failed authentication attempts and bans offending IPs using iptables/nftables. Protects SSH, Nginx, Apache, Postfix, and any service with log-based authentication.

Instructions

Step 1: Install

sudo apt install fail2ban
sudo systemctl enable fail2ban

Step 2: Configure

# /etc/fail2ban/jail.local — Custom configuration (never edit jail.conf)
[DEFAULT]
bantime = 1h
findtime = 10m
maxretry = 5
banaction = iptables-multiport

[sshd]
enabled = true
port = ssh
maxretry = 3
bantime = 24h

[nginx-http-auth]
enabled = true
port = http,https
maxretry = 5

[nginx-botsearch]
enabled = true
port = http,https
maxretry = 2
bantime = 7d

Step 3: Monitor

sudo fail2ban-client status               # list active jails
sudo fail2ban-client status sshd           # show banned IPs
sudo fail2ban-client set sshd unbanip 1.2.3.4   # unban
sudo fail2ban-client set sshd banip 5.6.7.8     # manual ban

Guidelines

  • Always create jail.local — jail.conf gets overwritten on updates.
  • Start conservative: 5 retries, 1h ban. Adjust based on logs.
  • For modern alternative with community threat sharing, consider CrowdSec.
  • Use fail2ban-regex to test custom filters before deploying.