Cannot make IM Audio/Video work through ISA

The following question was recently asked on the NG:

“Does anybody know how to allow the Video/Audio in MSN6.2 through ISA firewall. I have tested it OK between 2 laptops over the internet, but when I return one back to our SBS2003 LAN and try a video conf, I get the message: Your computer, Internet provider or network may not support audio conversations or video conversations.
Any Ideas ?????

Steve Foster replied as follows:

You will not get MSN Messenger video/audio to work through ISA. I don’t think ISA2004 will support it either.

The problem is that the audio/video connections are built dynamically, on random ports, directly between the two ends of the IM conversation, without going through the MSN IM servers. Both ends need to allow incoming connections on those random ports.

Many firewalls don’t support MSN Messenger audio/video.

This is one of the [self-inflicted] problems where uPnP helps (as it allows the client to reconfigure the firewall on demand). Personally, I don’t want my firewalls dynamically reconfigured, thank you very much…

Steve Foster [SBS MVP]

4 thoughts on “Cannot make IM Audio/Video work through ISA

  1. Hmmmm…

    It’s something I want to verify for myself, and I’m noting how a few others such as Tom Shinder tried recently and were unable to get it to work, but I’ve got some experience working with other protocols.

    Give me a couple weeks and sometime between now and the New Year I should be able to look at this, too and either report that I also failed or was able to find the solution others hadn’t found.

    Email me or find me direct if you don’t hear from me in this blog thread if you’re still interested…

    Tony Su

  2. Followup,

    I will try to get to this project as #3 in my list of relatively high priority but big projects, but if anyone reading this blog wants to get a jump on working on this issue, here are some building blocks probably no one else has looked at.

    First, because of my experience developing PDA enterprise applications I happen to have known about an application at called Portrait which for a long time was very "messenger-like" but was incompatible with existing Messenger clients at the time( It’s <very> cool.

    Imagine my surprise when I first setup LCS and discovered that the way Messenger supports Audio/Video is by bolting on Portrait!

    This leads me to believe that if you follow the Proxy Firewall instructions for Portrait you’ll be cooking

    (Click on FAQ > How to communicate trhough a firewall)

    Assuming outbound initiated connections,

    1. Configure Protocol Rules for destination ports Listen (8100), Video (8110), and Audio (8120)

    2. Install and configure a FW client if available

    3. Configure the HTTP Proxy settings properly (typically port 8080 will already be configured)

    We’ll see if this works, if it does it’s another big discovery!

    Tony Su

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