Microsoft appears to be pushing the .NET Messenger Service to HTTP
The changes to Messenger have continued this week with Microsoft blocking access to port 1863 (that’s the defacto port for Messenger) firstly with the servers known as messenger.hotmail.com (bay.*) on December 1st and then the bn1.gateway.messenger.live.com (bn.*) server(s) on December 3rd.
The ever ingenious dx put together a status page listing the various types of servers in the network and their current status.
In practical terms, this means that instead of using the MSN protocol directly, the protocol is now being funneled over an HTTP connection, just like a web page. The Microsoft Messenger clients will automatically give up on port 1863 and use HTTP without any prompting, so if you’re a Messenger Reviver user, you shouldn’t have to do anything. However, third-party clients may require triggering their HTTP mode options manually, and some don’t support the HTTP mode.
You’ll note that on dx’s status page, only the servers that are directly called using hostnames have port 1863 blocked. The more technically interested can force Messenger into using 1863 by using their local hosts file or setting up their own DNS server to redirect messenger.hotmail.com to one of the working bay servers, and bn1.gateway.messenger.live.com to one of the bn.* servers.