topic Re: SIP SDP NAT Issue in Network Security

SIP SDP NAT Issue

mloraditch — Tue, 31 Mar 2020 15:28:20 GMT

I am trying to connect to a provider over the internet.

The call comes up, but no audio. Per the provider my router is modifying the SIP SDP info to be the IP of the PAT address on the router instead of the 1 to 1 NAT.

I have tried turning SIP inspection on and off on my outbound ZBF config to no avail.

4321 Router on 16.07.01

There is not any other SIP traffic exiting this firewall nor will there be so I'm ok with doing some less conventional configuration if that is easier.

Re: SIP SDP NAT Issue

Cristian Matei — Tue, 31 Mar 2020 16:20:03 GMT

Hi,

You should be able to activate/deactivate the NAT ALG functionality for SIP, by making use of the "ip nat service sip" command. I never actually tested this, i had few cases with SIP and NAT, but it was required that NAT ALG does its job nd translates the payload as well. See this document for more reference.

Regards,

Cristian Matei.

Re: SIP SDP NAT Issue

mloraditch — Wed, 01 Apr 2020 12:18:20 GMT

Thanks will give that a go