Difference between revisions of "OS4X Fail2Ban integration"
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= Test = | = Test = | ||
| + | With the TLS server configured to [[OS4X_Core_configuration#TLS_server:_check_client_certificate_validity|check the TLS client certificate]], connect from an external host to your TLS listener port without a TLS client certificate: | ||
| + | openssl s_client -connect 192.168.40.24:6619 -tls1_2 | ||
| + | (with "<code>tls1_2</code>" for TLS 1.2, adopt to "<code>tls1_3</code>" if required). | ||
| + | |||
| + | The configured Fail2Ban log file should state something like this: | ||
Revision as of 11:02, 6 May 2026
Since OS4X 2026-05-06, OS4X offers a capability to write a logfile compatible to Fail2Ban. This system helps you to prevent attacks from externally.
Installation
On Debian based systems, it is very easy to install Fail2Ban:
apt update && apt -y install fail2ban
Configuration
Several configuration files and options must be set up for a working Fail2Ban environment.
OS4X Configuration
In Configuration -> Logging, define a path in Absolute path to Fail2ban logfile. This file must be writable by the OS4X daemon running user.
Fail2Ban filter
Create the following file:
/etc/fail2ban/filter.d/os4x.conf
with the following content:
[Definition] failregex = TLS error .+ during connect try from <HOST>: .* ignoreregex =
Fail2Ban jail
Create the following file:
/etc/fail2ban/jail.d/os4x.conf
with the following content:
[os4x] enabled = true port = 6619 filter = os4x logpath = /opt/os4x/tmp/fail2ban.log maxretry = 3 findtime = 600 bantime = 3600 action = %(action_mwl)s
Keep an eye on the following parameters:
port: Change the TCP port 6619 to your configured TLS listener port if necessary.logpath: This must be the same path as configured in OS4X.
In this default configuration, after three unsuccessful connections within ten minutes ("findtime = 600") the IP is being blocked on the given port for one hour ("bantime = 3600").
Restart Fail2Ban service
systemctl reload fail2ban
Test
With the TLS server configured to check the TLS client certificate, connect from an external host to your TLS listener port without a TLS client certificate:
openssl s_client -connect 192.168.40.24:6619 -tls1_2
(with "tls1_2" for TLS 1.2, adopt to "tls1_3" if required).
The configured Fail2Ban log file should state something like this: