How to measure how long NAT are kept "alive" by a router?

[oliv2831]

Hello,

1. How can I experimentally measure how long a router’s Network Address Translation is kept “alive” within router’s memory before being discarded ?
   If that matters, my question relates to both SIP and RTP traffic, mostly done with UDP.

Are there some boxes over the Internet that simply echo with a configurable delay, inbound udp traffic ?

2. Would you say that for most routers this NAT timeout equals 20s or so ?

3. Any pointer to learn more about this ?

Best regards

[david551]

@oliv2831

Are there some boxes over the Internet that simply echo with a configurable delay, inbound udp traffic ?

Unlikely, as they would be useful for DDOS.