fail2ban/config/filter.d/postfix.conf

# Fail2Ban filter for selected Postfix SMTP rejections
#
#

[INCLUDES]

# Read common prefixes. If any customizations available -- read them from
# common.local
before = common.conf

[Definition]

_daemon = postfix(-\w+)?/\w+(?:/smtp[ds])?
_port = (?::\d+)?

prefregex = ^%(__prefix_line)s<mdpr-<mode>> <F-CONTENT>.+</F-CONTENT>$

mdpr-normal = (?:\w+: reject:|(?:improper command pipelining|too many errors) after \S+)
mdre-normal=^RCPT from [^[]*\[<HOST>\]%(_port)s: 55[04] 5\.7\.1\s
            ^RCPT from [^[]*\[<HOST>\]%(_port)s: 45[04] 4\.7\.\d+ (?:Service unavailable\b|Client host rejected: cannot find your (reverse )?hostname\b)
            ^RCPT from [^[]*\[<HOST>\]%(_port)s: 450 4\.7\.\d+ (<[^>]*>)?: Helo command rejected: Host not found\b
            ^EHLO from [^[]*\[<HOST>\]%(_port)s: 504 5\.5\.\d+ (<[^>]*>)?: Helo command rejected: need fully-qualified hostname\b
            ^(RCPT|VRFY) from [^[]*\[<HOST>\]%(_port)s: 550 5\.1\.1\s
            ^RCPT from [^[]*\[<HOST>\]%(_port)s: 450 4\.1\.\d+ (<[^>]*>)?: Sender address rejected: Domain not found\b
            ^from [^[]*\[<HOST>\]%(_port)s:?

mdpr-auth = warning:
mdre-auth = ^[^[]*\[<HOST>\]%(_port)s: SASL ((?i)LOGIN|PLAIN|(?:CRAM|DIGEST)-MD5) authentication failed:(?! Connection lost to authentication server| Invalid authentication mechanism)
mdre-auth2= ^[^[]*\[<HOST>\]%(_port)s: SASL ((?i)LOGIN|PLAIN|(?:CRAM|DIGEST)-MD5) authentication failed:(?! Connection lost to authentication server)
# todo: check/remove "Invalid authentication mechanism" from ignore list, if gh-1243 will get finished (see gh-1297).

# Mode "rbl" currently included in mode "normal", but if needed for jail "postfix-rbl" only:
mdpr-rbl = %(mdpr-normal)s
mdre-rbl  = ^RCPT from [^[]*\[<HOST>\]%(_port)s: [45]54 [45]\.7\.1 Service unavailable; Client host \[\S+\] blocked\b

# Mode "rbl" currently included in mode "normal" (within 1st rule)
mdpr-more = %(mdpr-normal)s
mdre-more = %(mdre-normal)s

mdpr-ddos = (?:lost connection after(?! DATA) [A-Z]+|disconnect(?= from \S+(?: \S+=\d+)* auth=0/(?:[1-9]|\d\d+)))
mdre-ddos = ^from [^[]*\[<HOST>\]%(_port)s:?

mdpr-extra = (?:%(mdpr-auth)s|%(mdpr-normal)s)
mdre-extra = %(mdre-auth)s
            %(mdre-normal)s

mdpr-aggressive = (?:%(mdpr-auth)s|%(mdpr-normal)s|%(mdpr-ddos)s)
mdre-aggressive = %(mdre-auth2)s
                  %(mdre-normal)s

mdpr-errors = too many errors after \S+
mdre-errors = ^from [^[]*\[<HOST>\]%(_port)s$


failregex = <mdre-<mode>>

# Parameter "mode": more (default combines normal and rbl), auth, normal, rbl, ddos, extra or aggressive (combines all)
# Usage example (for jail.local):
#   [postfix]
#   mode = aggressive
#
#   # or another jail (rewrite filter parameters of jail):
#   [postfix-rbl]
#   filter = postfix[mode=rbl]
#
#   # jail to match "too many errors", related postconf `smtpd_hard_error_limit`:
#   # (normally included in other modes (normal, more, extra, aggressive), but this jail'd allow to ban on the first message)
#   [postfix-many-errors]
#   filter = postfix[mode=errors]
#   maxretry = 1
#
mode = more

ignoreregex = 

[Init]

journalmatch = _SYSTEMD_UNIT=postfix.service

# Author: Cyril Jaquier