The Shoreline Firewall, more commonly known as "Shorewall", is a 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 utility, Shorewall configures Netfilter 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; as a consequence, Shorewall can take advantage of Netfilter's connection state tracking capabilities to create a stateful firewall.

Shorewall is not a daemon. Once Shorewall has configured Netfilter, it's job is complete and there is no Shorewall code left running in the system. The /sbin/shorewall program can be used at any time to monitor the Netfilter firewall.