Fail2Ban iptables rules can be erased sometimes by disabling Plesk Firewall

Symptoms

When Fail2Ban is enabled and has already banned some IP addresses, its rules in iptables can be removed when Plesk Firewall is disabled.

Cause

Plesk bug PPPM-9399 that is planned to be fixed in future updates.

Resolution

Until the bug is fixed, use the workaround:

1. Connect to the server using SSH.

2. Open the file /etc/init.d/psa-firewall for editing and modify it as follows:

   • Before:

     if "$emergency"; then
     echo "$SERVICE_NAME: firewall successfully disabled"
     exit 0
     else
     echo "$SERVICE_NAME: failed to disable firewall"
     exit 1
     fi

   • After:

     if "$emergency"; then
     echo "$SERVICE_NAME: firewall successfully disabled"
     
     if [ "active" == `/bin/systemctl is-active fail2ban.service` ] ; then
     echo "$SERVICE_NAME: fail2ban will restart now."
     systemctl restart fail2ban.service &
     else
     echo "$SERVICE_NAME: fail2ban is not active and will not be restarted."
     fi
     exit 0
     
     else
     echo "$SERVICE_NAME: failed to disable firewall"
     exit 1
     fi

Note: After this modification, Fail2Ban service will be restarted on Plesk firewall disable action.