"This How-To is performed on a Debian Sarge 3.1 box, though the commands and syntax should work for any linux distro. Before you can configure iptables, you first must ensure that it has been compiled into the kernel, and that you have the proper userland utilities installed.
"You should have a config file from when the kernel was compiled. Grep'ing it for 'CONFIG_IP_NF' should produce '=y' or '=m' for most of the lines/options. Here you see that 'CONFIG_IP_NF_IPTABLES' was compiled as a kernel module..."
