I am a new user of iptables.

I want to add trigger port function in linux router by iptables.
In netfilter.org, I can't find any patch or new version support trigger port.
Do I miss anything ? If so, please tell me.

I find the some discussion about trigger port in openwrt forum.
The link of the patch is dead.
I don't know how to add trigger port function. Please advice.

Beside above, can anyone advice me the method to add trigger port function?