IPTABLES masquerading firewall is a script that automatically sets up basic masquerading during boot time, providing a self-contained solution for firewall protection.
One thing to note is that packet mangling has considerably changed under Linux kernel 2.4.x, including masquerading, firewalling, and port forwarding features. This document assumes that you are using modules, so if you aren't, you can disregard the code in the following script that tests for the loaded module.
The script itself is straightforward, with only three variables that you need to set: the full path to iptables, the network interface to masquerade on, and the machine or network to masquerade. You can set the network to masquerade as a hostname, IP address, or network mask.
The script also enables IP Masquerading in the kernel and tests if the iptable_nat module is loaded at boot time. If it is not loaded, the script will automatically load it. Finally, the script tests if existing MASQ rules exist at boot time and sets them if they don't.
Overall, I found the IPTABLES masquerading firewall to be a reliable and user-friendly option for those looking to enable basic masquerading quickly and easily.