Problem setting up voip behind firewall

[karweng]

Hi Guys,

I have a sonicwall pro 100 firewall within our LAN, I'm trying to setup a voip gateway in our office, and have setup all the correct ports for forwarding inward to voip gateway. As soon as I answer the call the call disconnect from voip gateway, I was told by the voip engineer that it is because our firewall translate to a different port to the other end. What I wanted to know if there's anyway to configure the firewall to forward the same port out as same port it came in?

 

[lmoe]

Did you try setting up the VOIP on a different network?
i.e. if the Firewall is on 192.168.0.# try putting the VOIP device on 192.168.1.# -- or any diffent 3rd octet.

LMC
IT/MIS
"Never stop learning.

 

[computerhighguy]

I cannot speak for every vendor, but I can for Cisco. Cisco has a signaling port and a communications port. It sounds like you are missing a port. I don't have expereince with your firewall, but I would imagine you set the port on the outside and the inside IP address. It will forward that port the way it is supposed to.

In the cisco world, there are can be serveral reasons for this. But typically it is an access control list issue.

Are you communicating with a VoIP provider or and individual phone? This will make a difference

What make and model phone system are you using?


It is what it is!!
__________________________________
A+, Net+, I-Net+, Certified Web Master, MCP, MCSA, MCSE, CCNA, CCDA, and few others (I got bored one day)

 

[jasonswan]

You need true stateful firewalling, is there an application layer inspection module on your sonicwall?
(I do know there is application layer inspection capabilites in IP-Tables)

On the cisco PIX the command is,

fixup protocol sip udp

Here is a brief intro on the cisco site....

http://www.cisco.com/en/US/products..._guide_chapter09186a008017278b.html#wp1078381

I hope that leads you in the right direction.

http://jason.swan.net

 

[liorz66]

In the Sonic, go to Access > Services.
there are 2 options you should play with:
Enable SIP Transformations
Enable H323Transformations
try to check/uncheck them. it also depends on the Sonic Firmware - if it's too old it currupts the packets.


the Sonic works fine for me!

 

[jasonswan]

That will be it!

Just out of curiosity...
Is Sonicwall based on IP-Tables or IPF?

http://jason.swan.net