Custom fail2ban Filter

Posted by Michael Robinson on Server Fault See other posts from Server Fault or by Michael Robinson
Published on 2012-10-05T00:31:12Z Indexed on 2012/10/05 3:40 UTC
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In my quest to block excessive failed phpMyAdmin login attempts with fail2ban, I've created a script that logs said failed attempts to a file: /var/log/phpmyadmin_auth.log


Custom log

The format of the /var/log/phpmyadmin_auth.log file is:

phpMyadmin login failed with username: root; ip: 192.168.1.50; url: http://somedomain.com/phpmyadmin/index.php
phpMyadmin login failed with username: ; ip: 192.168.1.50; url: http://192.168.1.48/phpmyadmin/index.php

Custom filter

[Definition]

# Count all bans in the logfile
failregex = phpMyadmin login failed with username: .*; ip: <HOST>;

phpMyAdmin jail

[phpmyadmin]

enabled  = true
port    = http,https
filter   = phpmyadmin
action   = sendmail-whois[name=HTTP]
logpath  = /var/log/phpmyadmin_auth.log
maxretry = 6

The fail2ban log contains:

2012-10-04 10:52:22,756 fail2ban.server : INFO   Stopping all jails
2012-10-04 10:52:23,091 fail2ban.jail   : INFO   Jail 'ssh-iptables' stopped
2012-10-04 10:52:23,866 fail2ban.jail   : INFO   Jail 'fail2ban' stopped
2012-10-04 10:52:23,994 fail2ban.jail   : INFO   Jail 'ssh' stopped
2012-10-04 10:52:23,994 fail2ban.server : INFO   Exiting Fail2ban
2012-10-04 10:52:24,253 fail2ban.server : INFO   Changed logging target to /var/log/fail2ban.log for Fail2ban v0.8.6
2012-10-04 10:52:24,253 fail2ban.jail   : INFO   Creating new jail 'ssh'
2012-10-04 10:52:24,253 fail2ban.jail   : INFO   Jail 'ssh' uses poller
2012-10-04 10:52:24,260 fail2ban.filter : INFO   Added logfile = /var/log/auth.log
2012-10-04 10:52:24,260 fail2ban.filter : INFO   Set maxRetry = 6
2012-10-04 10:52:24,261 fail2ban.filter : INFO   Set findtime = 600
2012-10-04 10:52:24,261 fail2ban.actions: INFO   Set banTime = 600
2012-10-04 10:52:24,279 fail2ban.jail   : INFO   Creating new jail 'ssh-iptables'
2012-10-04 10:52:24,279 fail2ban.jail   : INFO   Jail 'ssh-iptables' uses poller
2012-10-04 10:52:24,279 fail2ban.filter : INFO   Added logfile = /var/log/auth.log
2012-10-04 10:52:24,280 fail2ban.filter : INFO   Set maxRetry = 5
2012-10-04 10:52:24,280 fail2ban.filter : INFO   Set findtime = 600
2012-10-04 10:52:24,280 fail2ban.actions: INFO   Set banTime = 600
2012-10-04 10:52:24,287 fail2ban.jail   : INFO   Creating new jail 'fail2ban'
2012-10-04 10:52:24,287 fail2ban.jail   : INFO   Jail 'fail2ban' uses poller
2012-10-04 10:52:24,287 fail2ban.filter : INFO   Added logfile = /var/log/fail2ban.log
2012-10-04 10:52:24,287 fail2ban.filter : INFO   Set maxRetry = 3
2012-10-04 10:52:24,288 fail2ban.filter : INFO   Set findtime = 604800
2012-10-04 10:52:24,288 fail2ban.actions: INFO   Set banTime = 604800
2012-10-04 10:52:24,292 fail2ban.jail   : INFO   Jail 'ssh' started
2012-10-04 10:52:24,293 fail2ban.jail   : INFO   Jail 'ssh-iptables' started
2012-10-04 10:52:24,297 fail2ban.jail   : INFO   Jail 'fail2ban' started

When I issue:

sudo service fail2ban restart

fail2ban emails me to say ssh has restarted, but I receive no such email about my phpmyadmin jail. Repeated failed logins to phpMyAdmin does not cause an email to be sent.

Have I missed some critical setup? Is my filter's regular expression wrong?


Update: added changes from default installation

Starting with a clean fail2ban installation:

cp /etc/fail2ban/jail.conf /etc/fail2ban/jail.local

Change email address to my own, action to:

action = %(action_mwl)s

Append the following to jail.local

[phpmyadmin]

enabled  = true
port     = http,https
filter   = phpmyadmin
action   = sendmail-whois[name=HTTP]
logpath  = /var/log/phpmyadmin_auth.log
maxretry = 4

Add the following to /etc/fail2ban/filter.d/phpmyadmin.conf

# phpmyadmin configuration file
#
# Author: Michael Robinson
#

[Definition]

# 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>\S+)
# Values:  TEXT
#

# Count all bans in the logfile
failregex = phpMyadmin login failed with username: .*; ip: <HOST>;

# Option:  ignoreregex
# Notes.:  regex to ignore. If this regex matches, the line is ignored.
# Values:  TEXT
#

# Ignore our own bans, to keep our counts exact.
# In your config, name your jail 'fail2ban', or change this line!
ignoreregex =

Restart fail2ban

sudo service fail2ban restart

PS: I like eggs

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