How do I port forward in this situation?

[KUMARULLAL]

Hi,
I have 2 PBXs on the same local subnet. Both PBX's share the same WAN IP address. I want to assign 2 IAX2 Telex trunks to both these boxes.

                                                      pbx1(192.168.1.30)    
LinsysRV042(wan IP)----switch(192.168.1.0) <
                                                      pbx2(192.168.1.40)

Since IAX2 uses port 4569 only. How do I register both these boxes with Teliax?

 

[Linetux]

Unless you can tell Telex to use separate ports for each server behind your firewall/router, you can't.

Get additional external IP's to accomplish this, then forward each into its respective box.

 

[jroper]

Hi

I would disagree with Linutex's usually sage advice. IAX2 needs no ports open, or any port forwarding doing, unless you have endpoints registering to you.

In this case, you simply register each trunk as you would normally, and the NAT device will look after how to deliver the traffic, in the same way that it allows several people to surf the internet from behind one NAT device, and still delivers the right pages to the right person.


Joe

 

[dallas]

Hi,

I have a Firefly (Freshtel) softphone on the Freshtel network on a PC behind my NAT using port 4569 and my NAT has port forwarding of 4569 to my PiAF which has 10 Freshtel trunks. Both work fine. In fact I can call from the softphone, via the Freshtel network to my PiAF both on my local LAN and externally and everything works OK. I also have a Zoiper Biz softphone on the same PC using port 4569. Port 4569 is forwarded to PiAF only to allow Zoiper to register remotely.

Dallas

 

[blanchae]

Damn that IAX2, solves too many problems easily. I initially agreed with Linetux if you think of it as the provider must register into the local network. Then Linetux is correct. But if it is the PiaF server registering with the provider then Joe is correct.

A lawyer once told me that there is no such thing as truth - just how someone interprets it...

 

[dswartz]

Actually, I don't think that's quite right. The issue is specifically with SIP - IIRC, the source port for the SIP client is supposed to be 5060 as well as the destination. Given that, if two hosts behind a NAT gateway both try to register to the same provider, the SIP server there will see requests coming from the NAT IP and port 5060, and the return packets will not be able to get to the 2nd SIP client. This is presumably not a problem with IAX2. This is why (I believe) linetux suggested using different ports if possible.

 

[jroper]

Hi

Depending on the type of NAT device used, usually the more expensive ones, there is no reason why two SIP clients cannot register behind one NAT device either, but I would play it safe and have two IP addresses.

Because the RTP stream, and set-up and tear-down of the call in the IAX protocol all take place on the same port, NAT traversal is easy, and you don't have to worry about forwarding anything, unless you want endpoints to register to you.

Joe

 

[Linetux]

Actually, now that I think about it, it does depend on the direction of the registration.

If, for example, you have multiple servers behind the same IP NAT'ed, and you have IAX devices that need to register with those servers, each would need its own IP or port. However, in this example I didn't think it all the way though - there is no reason to port forward. The servers are registering with the provider, at which point the NAT device is going to give each additional device its own port via the magic of NAT.

To further some of the other comments regarding SIP below, depending on the NAT device, sometimes every device behind will register on a random port - other times the first device will register on 5060, then the following devices will have some random port assigned to them.