Port triggering using iptables

Is there any documentation for rules to set for port triggering using iptables ?

Also kernel configuration and iptables extensions configuration need for port triggering.

thanks in advance!

Can you describe what you mean by this?

I'm not sure your request needs to be in the developers section.

Are you simply seeking how to create firewall rules?

there is some information that new kernel has no support for ipt_TREGGER.c module at least it is not supported in new kernel (some kernel after 3.10 not sure after which kernel version).

If anyone has face similar issue to get port trigger working in OpenWRT (kernel space or user space )

It looks like NAT-penetrating workaround for some ancient protocols:
I wonder, is there demand for that nowadays?

https://www.comparitech.com/net-admin/port-forwarding-port-triggering-differences/[Great Expalanation.
Better security, great option for multiple gaming consoles using one ip through NAT.