Hi,
I've been having firewall issues such that some of my NATed users cannot hear audio from their softphones. Would enabling GKRouted, H245Routed and proxy enable help address these issues? In some cases the STUN feature of the dialer resolved issues to some users but some did not. Would any modifications in my gnugatekeeper help solve problem?
The problem is a known issue, configuring the GNUGK will have little effect. The problem is that most home routers are symmetric and on occasion they internally translate UDP ports numbers between the calling parties..
ie EP1 5001 ---> Router 65100 ---> EP2 5001
When using STUN, the NAT'd EP is reported to be available on port 5001 (which is true) however in fact it should be 65100 due to the router translation. So the audio never connects. STUN is really not suited for this type of router for this reason.
There really is only 4 possible solutions
1. Manually configure the router to port forward the required UDP port range. You will still need STUN and the NAT'd EPs will have to be at fixed LAN addresses and the WAN address of the router should also be fixed (most home internet IP addresses are dynamic).
2. Specify the Clients LAN address is in the Routers DMZ (not recommended)
3. Use something like ICE (Interactive Connectivity Establishment) new draft standard which incorporates STUN and few other tricks to force the connection
(don't know any applications that support it)
4. Use UPnP IGDv1 (www.upnp.org) to communicate between the NAT'd EP and the router to open and close port forwards as required and return external IP address (and any changes) to masquarade the EP. Does not require fixed LAN addresses and works on all NAT's where the router supports UPnP. Most SOHO Routers (Linksys,DLink,NetGear etc...) support UPnP but it is disabled by default.
A UPnP enabled EP detects the presence of a UPnP enabled router on the LAN and using XML messaging attempts to make the necessary configurations on the router.
I submitted to the OpenH323 project some months ago patches to add UPnP support for all OS's using the Intel Microstack. http://www.voxgratia.org/contrib.html#contrib_5 and this feature is also a standard component of our Windows DCOM development kit. There is a free download and a sample application (SimpleEP) that provides an example of how it works. It's fully compatible with GNUGK.
Contact me offlist if you require any further information.
Simon
Simon Home
ISVO (Asia) Pte Ltd
developer of the
Virteos H323COMtools
Win32 DCOM plugin based on the OpenH323 Stack
http://www.isvo.net
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