Video chat UPnP problem

Question

Hi there,
Since upgrading to Leopard, my wife and I have had no end of problems video chatting to others via iChat. Everything used to work fine in our older 10.4 installation.
When we connect in the morning, the first person to open up iChat is fine. They can video chat with others outside our local network no problem. However, the second person that connects can only text chat, video will not work.
Having read through the threads in here I think I can see the problem, but I don't know how to fix it. That's where I am hoping someone here can help.
When the first iChat client connects, the router automatically allocates a route through the NAT firewall on port 16402, the debug log says:
Mapped via UPnP, port 16402 to port 16402
This is fine, iChat works perfectly on that port configuration.
However, when the next person opens up iChat on the next computer, we get the following entry:
UPnP: TCPProc begin loop
UPnP eport 16402 already mapped: retry next
Mapped via UPnP, port 16406 to port 16402
UPnP: TCPProc end
UPnP shutdown
In this instance the port the UPnP process allocates is above the range that iChat can use, ie 16406. Hence when we try to video chat it won't work.
In a previous posting (http://discussions.apple.com/thread.jspa?threadID=1212655&tstart=0) Ralph Johns mentioned that:
+You will see iChat 4 uses only 10 Ports.+
+They are similar numbers but start from top Down (16402 being first choice)+
+(iChat 3 uses 4 from 20 ports bottom up with 16384 being first).+
My belief is that if my router worked the same in the older version of iChat, then the first port allocated would have been 16384, and then next would be 16388 - a port within the allowable iChat range. Hence everything worked fine with two clients.
Does anyone have any idea how I can change iChat to use to allocate ports for the bottom of the range, or adjust my router (a Netopia 3346N-VGx) to allocate UPnP ports in a downward direction?
Thanks in advance,
Simon

Answer 1

Hi,
That is odd.
I have yet to have failure myself that lists anything other than port 16402.
I use UPnP in my Netgear DG834G
I have one computer in Leopard and the other is in Tiger so although I can view the ports UPnP allocates in my Netgear I can not get two to use port 16402 potentially at the same time.
The next issue is that the Apple Doc says the ports will move down one port at a time.
Now iChat 3 moves up 4 ports at a time if the lower ones are busy.
So we have to ask is iChat 4 using some left over remains of iChat 3 ??
This is because it mat be presuming that 4 ports can not be used (16402-16405) and 16406 would be the next port.
I could do with knowing where you are getting those readouts from ?
The router or on the Mac in Console or Terminal ?
What make is the device ?
UPnP should allow the same ports to be used from different computers
However some devices may allocate a temporary Mapping and do what this looks like.
It looks like two issues.
1) UPnP is not working as expected.
2) Maybe the Upgrade has left part of iChat 3 there and is confusing the issue.
For this go to System/Library/ and show it in Coverflow mode.
Then check the Date Modified dates of Frameworks
Look inside and check InstantMessage.framework
Then inside that check iChatAgent's date
These should show the date that you installed Leopard.
USe the Back button until you are back at the System/Library
Now check the PrivateFramework folder and then the VideoConference.framework inside that.
Again it should be the install date.
Edit.
Go to Applications and click once on iChat
Use Apple key and I together to do a Get info.
Which version is it ?
10:36 PM Friday; December 7, 2007
Message was edited by: Ralph Johns (UK)