iptables-save [-M modprobe] [-c] [-t table]
ip6tables-save [-M modprobe] [-c] [-t table]
iptables-save and ip6tables-save are used to dump the contents of IP or IPv6 Table in easily parseable format to STDOUT. Use I/O-redirection provided by your shell to write to a file.
None known as of iptables-1.2.1 release
Harald Welte <email@example.com> Rusty Russell <firstname.lastname@example.org> Andras Kis-Szabo <email@example.com> contributed ip6tables-save.
The iptables-HOWTO, which details more iptables usage, the NAT-HOWTO, which details NAT, and the netfilter-hacking-HOWTO which details the internals.