cat /etc/fail2ban/filter.d/postfix-sasl.conf
# Fail2Ban filter for postfix authentication failures
#

[INCLUDES]

before = common.conf

[Definition]

_daemon = postfix(-\w+)?/(?:submission/|smtps/)?smtp[ds]

failregex = ^%(__prefix_line)swarning: [-._\w]+\[<HOST>\]: SASL ((?i)LOGIN|PLAIN|(?:CRAM|DIGEST)-MD5) authentication failed(:[ A-Za-z0-9+/:]*={0,2})?\s*$

ignoreregex = authentication failed: Connection lost to authentication server$

[Init]

journalmatch = _SYSTEMD_UNIT=postfix.service


# Author: Yaroslav Halchenko