It is a simplify interface to iptable, it allow therefore to configure
the firewall with rules easier to read than iptable ones.
Installation
# apt install ferm
Configuration
The configuration takes place in the /etc/ferm/ferm.conf file. By
default, only port 22 is open allowing SSH connexions:
proto tcp dport ssh ACCEPT;
To open port you only need to enter similar rules. Port can be specified by its
number or by the name of the service that it is associated with it. To
determined the name of the service associated with a port you just have to look
inside the /etc/services file.