Firewall Fundamentals

The more formal name of iptables is NetFilter. NetFilter requires the use of a Linux kernel version 2.4 or greater and was designed as the replacement for the previous firewall code in the Linux kernel prior to 2.4. In addition to the kernel modules for the NetFilter code, the iptables utility is needed to configure and manipulate the firewall rules. These two elements are the only items required for getting a firewall and NAT device based on NetFilter's working under Linux.