arno-iptables-firewall is an iptables configuration script with support for both IPv4 & IPv6. In general,
it should not be called directly, but rather should be invoked via /etc/init.d/arno-iptables-firewall or
systemctlCOMMANDarno-iptables-firewall.service, depending on the init system in use. While it is
extremely easy to set up a basic firewall one can nevertheless configure it to meet quite complex
requirements.
All available options are explained in the extensively documented configuration file.
As a bare minimum the external interface of the system needs to be set up properly in the firewalls
configuration (EXT_IF). The default behavior of the firewall is to deny all incoming connections.
Instead of editing the main configuration file, it is recommended to put configuration snippets into
.conf files to be placed in the configuration directory. These are sourced after the main configuration
file has been read and can be used to override previous (default) configurations.
For additional requirements not covered by the configuration file and not coverable by configuration
snippets custom iptables rules can be placed in a custom rules file. This file is automatically parsed by
the service script.
Logs are written to a dedicated log file if rsyslogd is in use. The arno-fwfilter script can be used to
make the firewall logs more readable for humans (see manpage).
Several plugins implementing advanced features come with the firewall script. Each of them brings its own
configuration file to be found in the plugins configuration directory.