Fixing Windows Media Services behind a Firewall with SBS 2008

For as long as I’ve run a personal SBS server, I have run a Windows Media feed of my local police radio traffic, using a scanner plugged into my server.  For the better part of a year, I haven’t been able to do this;  Everything bad that could happen to my feed, has, from a broken radio, to a broken server, and now Windows Media Services 9.5 is broken!

WMS 9.5 is part of Windows Server 2008 (and SBS 2008) and blogger Random explains the problem:

I’ve talked to a number of people that are having problems streaming from Windows Media Services 2008 on Windows Server 2008 when the server is behind a NAT firewall, some proxies, or load balancers. Clients on the internal network work just fine. In a network trace you’ll see at WMS is returning a 503 Service Unavailable as the first response to the RTSP DESCRIBE or HTTP GET.

WMS is doing a DNS query for the domain name in the RTSP or HTTP request when the request is not the local NetBIOS, local DNS, or local IP. If a WMP client is requesting content through a NAT or similar device (such as some proxies and load balancers that hides or translate an external URL to an internal URL), the requested address might be something like mms://streaming.contoso.com/live. However internally the server name might be WMS01 or WMS01.corp.contoso.com. This generally is only going to happen if you’re using Network Address Translation.

WMS 9.5 now contains a cache/proxy in the box. What’s happening is when WMS doesn’t recognize the requested URL as itself it is assuming that the request may be a proxy request. This happens even if the cache/proxy plug-in is disabled. Because internal clients would use the internal IP, NetBIOS, or DNS name, the server recognizes those request as intended for the local server itself.

The workaround is to edit the HOSTS file on the WMS server, in c:\windows\system32\drivers\etc\ and add the folllowing line:

127.0.0.1   <public address you are streaming from>

In my case this is:

127.0.0.1   n1kgh.gotdns.org

This address is a dynamic IP I maintain with dyndns.org (and my ham radio call!)

It works fine.  In fact, I have had excellent uptime, as seen in the screenshot above;  my stream ran for 15 days, only interrupted by a patch.

You can hear the stream on Windows Media at mms://n1kgh.gotdns.org/salemscanner  It includes Salem police, fire and surrounding communities.

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