Hello ;
You can find a set of i-MSCP listener file for i-MSCP >= 1.2.0 in this repository.
List of available listener files inside this repository
Listener::Apache2::DualStack
The listeners.d/10_apache2_dualstack.pl listener file provide dual stack support for Apache2.
Listener::Postfix::Tuning
The listeners.d/10_postfix_tuning.pl listener file allow to tune Postfix configuration files ( main.cf and master.cf ).
Listener::System::Hosts
The listeners.d/10_system_hosts.pl listener file allow to add host entries in the system hosts file ( eg. /etc/hosts ).
