I have decided to do a few tests on the XP firewall, now I have in the settng area msmsgs then a UDP, ICMP OR TCP port number now by disabing these and stopping them from accessing the internet it turns my PC into stealth, however what do they close?
In other words, you have simply closed down the ports used by Windows Messenger. You can achieve the same effect by closing down or disabling the Windows Messenger service. As I have absolutely no need for either Windows Messenger or Messenger services, they are both set to Disabled on my main XP PC.
MSN Messenger opens 14 separate ports (see below). If you have closed them all, it will not work at all. If you have left the chat port open, you will still be able to chat, if you have left the video port open, you will still be able to video-conference, etc.
A port can still be open, but stealthed. Steve Gibson's site explains quite clearly what 'stealthed' means.
MSN Messenger requires TCP ports 1863, 5060, 1503, 3389, 6891, 6892, 6893, 6894, 6895, 6896, 6897, 6898, 6899 and 6900 to be open.