topic Re: Voip external server in General Topics

Voip external server

WLitdepartment — Thu, 03 Oct 2013 07:41:39 GMT

I'm experiencing an issue with a connection to an external voip server.

Directly attached to a PA-500 ethernet port there is a patton (fxo voip appliance).

Now, I'm allowing any traffic to outside, any application.

When I surf from that interface I can access external sites, but the issue seems to be NAT.

Voip uses port 5060 udp.

I can see the packets reaching the external server (that I manage) and they are forwarded back, but on the PA they are not present.

I tried different NAT types, but none of them seems to be working properly.

Does anyone experienced the same issue?

Does anyone know how to solve the problem of udp coming back to the internal interface of the firewall?

Thanks to all of you,

Pietro

Re: Voip external server

dpalani — Mon, 07 Oct 2013 14:57:03 GMT

Is the proxy server able to establish a sip session successfully with the external server ? Is the proxy server a nat aware device( does it know its public ip address ) ?

Re: Voip external server

shasnain — Mon, 07 Oct 2013 15:07:21 GMT

have you tried a static bi-directional nat for this traffic.

Re: Voip external server

_slv_ — Mon, 07 Oct 2013 17:45:49 GMT

Please read this topichttps://live.paloaltonetworks.com/message/15066#15066

it could help you - try to use application override

regards

SLawek

Re: Voip external server

WLitdepartment — Tue, 08 Oct 2013 13:29:40 GMT

The external server is well known by the patton.

It arrives and the landing packet reaches the target.

When the packet is sent back everything stops.

Now I'm trying the hint given by slv.

Re: Voip external server

sd@censhare.com — Sat, 06 Sep 2014 02:45:40 GMT

Last post on Oct 8, 2013 6:29 AM but I got the same issue and maybe it will help the next person

My Environment:

PA-500 with PanOS 6.0.4

External voip Server from nfon incl snom phones + patton.

Hints in other discussions:

Application override -> problem still exist

Bidirectional nat -> problem still exist

ALG disabled -> problem still exist
Packet capture -> I saw my packages in the "drop" log and after hours of stupid investigation, it was only the route back to my snom-clients. The crazy thing is that I was able to see all the outgoing traffic and everything looked fine but due to the misconfiguration of my route my packages were dropped and I was NOT able to see them in the Traffic monitor. Only a packed captured helped

I know this is not the global solution but maybe someone is using PAN OS 6.0.x and nfon as a voip provider too. (ALG possible!)