Ban Specific IP Manually with fail2ban

Now that I'm monitoring my logs using cetralised RSyslog, I regularly notice SSH attacks right when and as they happen. When it becomes obvious that someone's trying to brute-force SSH, I don't always wait to let fail2ban fix the issue – sometimes I ban the offending IP myself.

How To Ban Specific IP with fail2ban

Assuming a standard install, we'll use the fail2ban-client command to notify sshd jail module to ban a specific IP.

Here's how it works:

root@s1:/etc/fail2ban # fail2ban-client -vvv set sshd banip 202.70.66.228
30 7F0B121F6640 fail2ban.configreader     INFO  Loading configs for fail2ban under /etc/fail2ban
30 7F0B121F6640 fail2ban.configreader     DEBUG Reading configs for fail2ban under /etc/fail2ban
31 7F0B121F6640 fail2ban.configreader     DEBUG Reading config files: /etc/fail2ban/fail2ban.conf
31 7F0B121F6640 fail2ban.configparserinc  INFO    Loading files: ['/etc/fail2ban/fail2ban.conf']
31 7F0B121F6640 fail2ban.configparserinc  TRACE     Reading file: /etc/fail2ban/fail2ban.conf
31 7F0B121F6640 fail2ban.configparserinc  INFO    Loading files: ['/etc/fail2ban/fail2ban.conf']
31 7F0B121F6640 fail2ban.configparserinc  TRACE     Shared file: /etc/fail2ban/fail2ban.conf
32 7F0B121F6640 fail2ban                  INFO  Using socket file /var/run/fail2ban/fail2ban.sock
32 7F0B121F6640 fail2ban                  INFO  Using pid file /var/run/fail2ban/fail2ban.pid, [INFO] logging to SYSLOG
32 7F0B121F6640 fail2ban                  HEAVY CMD: ['set', 'sshd', 'banip', '202.70.66.228']
48 7F0B121F6640 fail2ban                  HEAVY OK : 1
48 7F0B121F6640 fail2ban.beautifier       HEAVY Beautify 1 with ['set', 'sshd', 'banip', '202.70.66.228']
1
48 7F0B121F6640 fail2ban                  DEBUG Exit with code 0 

Once you become comfortable, you can omit the -vvv option and skip all this verbose output:

root@s1:/etc/fail2ban # fail2ban-client set sshd banip 202.70.66.229
1

That's it for today! Have fun!

See Also

• fail2ban how-to
• Log fail2ban to syslog
• Centralised RSyslog
• RSyslog file by hostname
• SSH server
• SSH reference

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