Fail2ban for SSH

Fail2ban helps protect SSH by monitoring auth logs and banning IPs after repeated failed login attempts.

Install

Ubuntu/Debian:

sudo apt update
sudo apt install -y fail2ban

RHEL/CentOS:

sudo dnf install -y fail2ban

Enable and start

sudo systemctl enable fail2ban
sudo systemctl start fail2ban
sudo systemctl status fail2ban

Configure SSH jail (recommended: use jail.local)

Create or edit /etc/fail2ban/jail.local:

[sshd]
enabled = true
port = ssh
logpath = /var/log/auth.log
backend = systemd
maxretry = 5
findtime = 10m
bantime = 1h

For RHEL-like systems, logpath is usually /var/log/secure.

Apply changes

sudo systemctl restart fail2ban

Check status and banned IPs

sudo fail2ban-client status
sudo fail2ban-client status sshd

Unban an IP

sudo fail2ban-client set sshd unbanip <IP_ADDRESS>

Useful notes

• Keep your own admin/VPN IP in ignoreip to avoid locking yourself out.
• Fail2ban is a layer, not a replacement: also use SSH keys and disable password login when possible.
• Test with maxretry and findtime values that match your server’s risk profile.