A Kimai 2 plugin, which logs an error message for every failed login attempt to a dedicated logfile.

This logfile can be analyzed by fail2ban to block access and prevent authentication attacks.

First clone it to your Kimai installation plugins directory:

cd /kimai/var/plugins/
git clone https://github.com/Keleo/Fail2BanBundle.git

And then rebuild the cache:

cd /kimai/
bin/console cache:clear
bin/console cache:warmup

You could also download it as zip and upload the directory via FTP:

/kimai/var/plugins/
├── Fail2BanBundle
│   ├── Fail2BanBundle.php
|   └ ... more files and directories follow here ... 

You should know how to use and configure fail2ban, we cannot help with that part! Having said that, here are some possible rules for your fail2ban configuration.

First the Kimai specific filter:

#/etc/fail2ban/filter.d/kimai2.conf
[Definition]
failregex = fail2ban.ERROR: <HOST> \[.*\] \[.*\]$

And the additional jail.local for Kimai2:

#/etc/fail2ban/jail.local
[kimai2]
enabled   = true
filter    = kimai2
logpath   = /var/www/kimai2/var/log/fail2ban.log
port      = http,https
bantime   = 600
banaction = iptables-multiport
maxretry  = 3

Now touch the file to make sure it exists:

touch /var/www/kimai2/var/log/fail2ban.log

• Bundle inspired by this blog entry
• Thanks also to @BeckeBauer for the idea and the initial try
• Find config documentation in the fail2ban wiki