sshd-obvious configuration for fail2ban Allows for a maxretry=1 for obvious hack attempts while leaving maxretry=3 available for possible mistakes.

sshd-obvious.conf

# Fail2Ban configuration file
#
# Author: Cyril Jaquier
#
# $Revision$
#

[INCLUDES]

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


[Definition]

_daemon = sshd

# Option:  failregex
# Notes.:  regex to match the password failures messages in the logfile. The
#          host must be matched by a group named "host". The tag "<HOST>" can
#          be used for standard IP/hostname matching and is only an alias for
#          (?:::f{4,6}:)?(?P<host>[\w\-.^_]+)
# Values:  TEXT
#
failregex = ^%(__prefix_line)sUser .+ from <HOST> not allowed because not listed in AllowUsers$
            ^%(__prefix_line)sAddress <HOST> .* POSSIBLE BREAK-IN ATTEMPT!*\s*$
            ^%(__prefix_line)sUser .+ from <HOST> not allowed because none of user's groups are listed in AllowGroups\s*$
  	
# Option:  ignoreregex
# Notes.:  regex to ignore. If this regex matches, the line is ignored.
# Values:  TEXT
#
ignoreregex =