When using TCP, is a new entry in the NAT table created when a connection is made? and is an entry in the NAT table removed when a connection is closed?

If I am correct, what happens if both communicating devices were unplugged (and so no FIN packet or RST packet is sent), will the NAT table entry for the connection remain in the NAT table forever?

1 Answer 1


It varies by manufacturer, but they all have a timer mechanism that deletes stale translations.

  • The timeout can often be configured (TCP/UDP aging).
    – Zac67
    Commented Aug 28, 2022 at 15:26

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