Posted on 2006-06-17
Last Modified: 2008-01-09
I am new to ISA 2004 firewall, I want to allow messenger but don't want to use file transfer using messanger. Can any body help me .
Question by:samir_santra
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LVL 51

Expert Comment

by:Keith Alabaster
ID: 16927344
MSN uses the following port range (6891-6900 on tcp) for file transfer. try blocking these ports from local host & internal to external

Author Comment

ID: 16928877
This port information is critical. Thank you.

Does all messenger service use the same port range.
Should I apply this on the firewall policy ?
Also can you please guide me how to block this .

LVL 51

Expert Comment

by:Keith Alabaster
ID: 16929062

Internet or edge facing firewalls should be configured with a default 'Deny' policy and contain 'Permit' policies for only needed services and applications. With respect to the W32.Bropia.J and W32.Bropia.L worms certain MSN Messenger file transfers can be blocked at the Internet firewall by removing any permit rules that allow TCP port 6891-6900 traffic. Note: Blocking TCP ports 6891-6900 will not block MSN Messenger instant messages as they flow over TCP port 1863.

This range will block most MSN transfers but not necessarily all. The new versions have proxy settings for both http and socks traffic but is a good start.
I would make a new policy for this range and apply a deny for it.

create a new protocol, give it a name, select the port range for outgoing tcp 6891 to 6900 and save it
Create a new access rule, give it a name and select deny, select the new protocol you created, from internal & local host to external, all users.
Apply the policy
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Author Comment

ID: 16957686
thanks msn-fle transfer is blocked but still I can send files through yahoo messanger. my requirement is that any messanger should work but all file transfer should be blocked.
LVL 51

Accepted Solution

Keith Alabaster earned 250 total points
ID: 16961831
There is no single policy that will cover every messenger.
yahoo file transfer uses this server


Create a deny rule to this url

Expert Comment

ID: 16967201
for your particular purpose you will require to do some study,

Either you search all the messenger sites and lok for ports used by them for File transfers or install a sniffer on ur machine and try seeing which ports its using to do that....

LVL 51

Expert Comment

by:Keith Alabaster
ID: 16981717
Thankyou :)

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