UDP hole timeout is refreshed also upon receiving data?

[Alessio Pace]

Hi,

imagine I have a node C behing a firewall contacting a public node P
by means UDP. In this way, C opens a hole for P to reply back within a
timeout (the C's hole timeout).

I was wondering what is the most commonly found behaviour for
firewalls/routers in the case when is just P that from this point
sends datagrams to C (unidirectional communication P-->C): does C's
firewall/router drop the communication after a timeout, or does it
"refresh" the hole at every incoming datagram from P?

Thanks a lot in advance.

Best regards,
Alessio Pace.