Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

What firewall rules do I need to apply to block MSN Messenger? I've applied the following:

I've also blocked all traffic on port 1863.

Still able to sign-in.

Any suggestions?

share|improve this question
up vote 2 down vote accepted

Far better to prevent MSN Messenger from being run; it's stopping the problem at source.

Blocking some of those sites - particularly - could impact on other services, such as your ability to access, MSDN or Technet.

share|improve this answer

Blocking traffic on the specific port will do little as the basics of MSN Messenger can operate over HTTP these days, so only blocking the relevant hosts (or ranges of hosts) will work.

To find out what hosts it is communicating with you can use a tool such as tcpdump, though this may be a cat-and-mouse chase as you block a couple of hosts and it uses another until you've got them all covered.

share|improve this answer
As David says; MSN Messenger can operate over Port 80 if all it's "normal" ports are blocked. Good for the user but a nightmare for the SysAdmin. – DilbertDave Aug 4 '09 at 9:33
This link is quite old but might be useful - at least it provides alternatives to Port Blocking: – DilbertDave Aug 4 '09 at 9:41
IME, the very most foolproof method is to block the known ports and then proxy filter HTTP. – Dan Carley Aug 4 '09 at 10:00

if you are using a applciation proxy you can block messenger there, or you can create a GPO with software restrictions to prevent messenger from running.

share|improve this answer

Use tcpdump to find out what type of traffic does MSN messenger generate. Than block it ;)

share|improve this answer

Add MSN Messenger TCP - 1863,6891-6900,6901, UDP - 1863,5190,6901 to your firewall rules.

Also block access to the web messenger service.

You can also block it from being run via group policy or simply remove it from offending machines.

This doesn't even hit the tip of the iceberg when you have proxies and VPNs to deal with.

share|improve this answer

I Tried to block with HTTP Headder inspections from TMG and the solution not worked. It's basically complex to block this though it's microsoft product. What I did was prevent it running using a GPO. That killed it from the root.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.