xtables-addons(8)

Name
Xtables-addons — additional extensions for iptables, ip6tables, etc.

Targets

Matches

See also
iptables(8), ip6tables(8), iptables-extensions(8), iptaccount(8)

For developers, the book "Writing Netfilter modules" at http://inai.de/documents/Netfilter_Modules.pdf provides detailed information on how to write such modules/extensions.