SoL (Server optimized Linux) is a Linux distribution completely independent from other Linux distributions. It was built from the original source packages and is optimized for heavy-duty server work. It contains all common server applications, and features XML boot and script technology that makes it easy to configure and make the server work.
Firewall is a set of scripts (firewall, fwup, and fwdown) that implement an ipchains firewall and various forms of network address and port translation. All you have to do is read the policy file and edit it to reflect your topology and filtering policy. It supports many different types of network topology (single host, traditional forwarding, masquerading, port forwarding, alias port forwarding and NAT), up to 10 untrusted interfaces each with their own policy, and over 50 network applications. It also supports centralised administration of multiple remote firewalls (meta-firewall).