DOKK / manpages / debian 12 / natpmpc / natpmpc.1.en
natpmpc(1) General Commands Manual natpmpc(1)

natpmpc - NAT-PMP library test client and mapping setter.

Display the public IP address:
natpmpc

Add a port mapping:
natpmpc -a <public port> <private port> <protocol> [lifetime]

In order to remove a mapping, set it with a lifetime of 0 seconds. To remove all mappings for your machine, use 0 as private port and lifetime.