Duplicate of original post: https://troubleshoot-coltpython.blogspot.com/2013/11/ubuntu-fail2ban-fails-to-parse-apache.html
I was trying to setup Fail2ban to block WordPress login bruteforce attacks, but Fail2ban somehow failed to parse access.log
When parsing log file with command:
fail2ban-regex /var/log/apache2/access.log /etc/fail2ban/filter.d/apache-wp-login.conf
CPU rises to 100% usage until I kill the process. I made a quick fix – workaround with redirecting needed content from access.log to another log file.
My setup is as follows:
OS: Ubuntu Server 12.04 LTS
# Fail2Ban configuration file # Author: Cyril Jaquier # $Revision$ [Definition] # Option: loglevel # Notes.: Set the log level output. # 1 = ERROR # 2 = WARN # 3 = INFO # 4 = DEBUG # Values: NUM Default: 3 # loglevel = 4 # Option: logtarget # Notes.: Set the log target. This could be a file, SYSLOG, STDERR or STDOUT. # Only one log target can be specified. # Values: STDOUT STDERR SYSLOG file Default: /var/log/fail2ban.log # logtarget = /var/log/fail2ban.log # Option: socket # Notes.: Set the socket file. This is used to communicate with the daemon. Do # not remove this file when Fail2ban runs. It will not be possible to # communicate with the server afterwards. # Values: FILE Default: /var/run/fail2ban/fail2ban.sock # socket = /var/run/fail2ban/fail2ban.sock
We add a new entry for WordPress
Add configuration to /etc/fail2ban/jail.conf
[apache-wp-login] enabled = true port = http,https filter = apache-wp-login logpath = /var/log/apache2/apache-wp-login.log maxretry = 3 findtime = 60
Now me make new filter for WordPress. Some servers logs are in different format so we have to make different regex entries. These are two most common configurations:
Log format example 1:
www.domain.si:80 22.214.171.124 - - [08/Nov/2013:13:20:46 +0100] "POST /en/wp-login.php HTTP/1.1" 200 1784 "http://www.domain.si/en/wp-login.php" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1623.0 Safari/537.36"
Log format example 2:
126.96.36.199 - - [08/Nov/2013:13:40:12 +0000] "POST /wp-login.php HTTP/1.1" 200 1756 "http://domain.wordpress.com/wp-login.php" "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:25.0) Gecko/20100101 Firefox/25.0"
For log format example 1 use:
[Definition] failregex = ^[^\:]+\:80 <HOST> .* "POST ignoreregex =
ATTENTION! Don’t apply this filter to default access.log, it would block all POST request, not only WordPress. Only use it with modified log file we will create bellow.
For log format example 2 use:
failregex = <HOST>.*] "POST /wp-login.php
ATTENTION! Don’t apply this filter to log format example 1, it would block your own server, because <HOST> regex would match your domain (www.domain.si).
Now we create new log file for parsing (/var/log/apache2/apache-wp-login.log). We only want to filter out POST requests for wp-login.php and write them to new log file called apache-wp-login.log
tail --follow=name /var/log/apache2/access.log | grep --line-buffered wp-login.php &amp;gt; /var/log/apache2/apache-wp-login.log &amp;amp;
Add this command to /etc/rc.local so it would run at reboot:
#!/bin/sh -e # # rc.local # # This script is executed at the end of each multiuser runlevel. # Make sure that the script will "exit 0" on success or any other # value on error. # # In order to enable or disable this script just change the execution # bits. # # By default this script does nothing. # Fail2ban WordPress Login tail -f /var/log/apache2/access.log | grep --line-buffered wp-login.php > /var/log/apache2/apache-wp-login.log & exit 0