# Fail2Ban filter for sendmail spam/relay type failures
#
# Some of the below failregex will only work properly, when the following
# options are set in the .mc file (see your Sendmail documentation on how
# to modify it and generate the corresponding .cf file):
#
# FEATURE(`delay_checks')
# FEATURE(`greet_pause', `500')
# FEATURE(`ratecontrol', `nodelay', `terminate')
# FEATURE(`conncontrol', `nodelay', `terminate')
#
# ratecontrol and conncontrol also need corresponding options ClientRate:
# and ClientConn: in the access file, see documentation for ratecontrol and
# conncontrol in the sendmail/cf/README file.

[INCLUDES]

before = common.conf

[Definition]

_daemon = (?:(sm-(mta|acceptingconnections)|sendmail))

failregex = ^%(__prefix_line)s\w{14}: ruleset=check_rcpt, arg1=(?P<email><\S+@\S+>), relay=(\S+ )?\[<HOST>\]( \(may be forged\))?, reject=(550 5\.7\.1 (?P=email)\.\.\. Relaying denied\. (IP name possibly forged \[(\d+\.){3}\d+\]|Proper authentication required\.|IP name lookup failed \[(\d+\.){3}\d+\])|553 5\.1\.8 (?P=email)\.\.\. Domain of sender address \S+ does not exist|550 5\.[71]\.1 (?P=email)\.\.\. (Rejected: .*|User unknown))$
            ^%(__prefix_line)sruleset=check_relay, arg1=(?P<dom>\S+), arg2=<HOST>, relay=((?P=dom) )?\[(\d+\.){3}\d+\]( \(may be forged\))?, reject=421 4\.3\.2 (Connection rate limit exceeded\.|Too many open connections\.)$
            ^%(__prefix_line)s\w{14}: rejecting commands from (\S* )?\[<HOST>\] due to pre-greeting traffic after \d+ seconds$
            ^%(__prefix_line)s\w{14}: (\S+ )?\[<HOST>\]: ((?i)expn|vrfy) \S+ \[rejected\]$
            ^(?P<__prefix>%(__prefix_line)s\w+: )<[^@]+@[^>]+>\.\.\. No such user here$<SKIPLINES>^(?P=__prefix)from=<[^@]+@[^>]+>, size=\d+, class=\d+, nrcpts=\d+, bodytype=\w+, proto=E?SMTP, daemon=MTA, relay=\S+ \[<HOST>\]$


ignoreregex =


[Init]

journalmatch = _SYSTEMD_UNIT=sendmail.service

# "maxlines" is number of log lines to buffer for multi-line regex searches
maxlines = 10

# DEV NOTES:
# 
# Regarding the last multiline regex:
#
# There can be a nunber of non-related lines between the first and second part
# of this regex maxlines of 10 is quite generious. Only one of the 
# "No such user" lines needs to be matched before the line with the HOST.
#
# Note the capture __prefix, includes both the __prefix_lines (which includes
# the sendmail PID), but also the \w+ which the the sendmail assigned mail ID.
#
# Author: Daniel Black and Fabian Wenk