The Shoreline Firewall, more commonly known as "Shorewall", is high-level tool for configuring Netfilter.
You describe your firewall/gateway requirements using entries in a set of configuration files.
Shorewall reads those configuration files and with the help of the iptables, iptables-restore, ip and
tc utilities, Shorewall configures Netfilter and the Linux networking subsystem to match your requirements.
Shorewall can be used on a dedicated firewall system, a multi-function gateway/router/server or on a
standalone GNU/Linux system. Shorewall does not use Netfilter's ipchains compatibility mode and can thus
take advantage of Netfilter's connection state tracking capabilities.
Shorewall is not a daemon. Once Shorewall has configured the Linux networking subsystem, its job is complete and
there is no "Shorewall process" left running in your system. The /usr/sbin/shorewall program can be used at
any time to monitor the Netfilter firewall.