Fail2Ban
About
Fail2Ban is a small program which scans log files real-time and takes actions when hacking attempts are detected. More information about Fail2Ban can be found here
Protected services
Kolmisoft has implemented protection for these services:
- Asterisk - protects from brute-force registration attacks
- Apache - protects from scanning bots which try to access not existing address, for example http://YOUR_IP/MorAdmin (correct end with Kolmisoft software is "moradmin") - Coming soon.
- SSH - protects from brute-force attacks.
Installation
Custom modifications
Remember to save backups for your custom modifications to Fail2Ban as automated installation/update/upgrade scripts can overwrite them.
If you have suggestions how Fail2Ban rules can be extended - please write to mindaugas.mardosas@kolmisoft.com
Modifying existing rules
All filters are enabled/disabled in /etc/fail2ban/jail.conf
To extend an existing filter please go to /etc/fail2ban/filter.d and open the required file. For example we will take /etc/fail2ban/filter.d/asterisk.conf:
bad patterns are specified at failregex variable as following:
failregex = NOTICE.* .*: Registration from '.*' failed for '<HOST>' - Wrong password
NOTICE.* .*: Registration from '.*' failed for '<HOST>' - Peer is not supposed to register
NOTICE.* .*: Registration from '.*' failed for '<HOST>' - No matching peer found
NOTICE.* .*: Registration from '.*' failed for '<HOST>' - Username/auth name mismatch
NOTICE.* .*: Registration from '.*' failed for '<HOST>' - Device does not match ACL
NOTICE.* <HOST> failed to authenticate as '.*'$
NOTICE.* .*: No registration for peer '.*' \(from <HOST>\)
NOTICE.* .*: Host <HOST> failed MD5 authentication for '.*' (.*)
NOTICE.* .*: Failed to authenticate user .*@<HOST>.*
you can add here your own.
Testing changes
You can test your new rules using fail2ban-regex tool as following:
fail2ban-regex /path/to/your/log/file/to/scan /etc/fail2ban/filter.d/asterisk.conf
This tool will show you how many matches were found and what regexp's were used.
Moving changes to production
Restart fail2ban:
/etc/init.d/fail2ban restart
See also
