I have one customer, which use cisco ASA5520 , and after testing, I found that only stun protocol is not supported in their network. classic-stun can work functionally, but only stun can not work,
I am not sure why, anybody can give some advice?
stun only can see binding request, but has no binding response,
for example, customer computer is A, my machine is B, using wireshark in A, we can see A send udp stun package to B,
I can not catch udp package at machine B with tcpdump.
What is your version? STUN has been supported since Release 9.6(2).
You can now inspect STUN traffic for WebRTC applications including Cisco Spark. Inspection opens pinholes required for return traffic.
We added or modified the following commands: inspect stun , show asp drop , show conn detail , show service-policy inspect stun .
Now that you can see A send udp stun package to B, is there any equipment between A and B?
STUN is supported from 9.6(2) and later versions, And ASA 9.1(x) was the final version for the ASA 5510, 5520, 5540, 5550, and 5580.
The ios version does not meet the requirements, so the ASA5520 does not support stun.
OK, I'm glad that your problem is solved, you can ignore it.