Re: blocking some common TCP/UDP ports

From: Steven L Umbach (n9rou_at_nospam-comcast.net)
Date: 02/25/04 

Date: Tue, 24 Feb 2004 23:20:23 GMT

You may be doing this already, but it is best to have a block all default rule for
outbound access and then add the allowed exceptions. I will leave a link or two, but
you may have better luck searching http://google.com for the associated ports such as
"Yahoo messenger ports" or try to track them down yourself by using something like
TCPView [free from SysInternals] to see what ports are used on a test computer or
view your firewall logs. --- Steve

http://www.sysinternals.com/ntw2k/source/tcpview.shtml
http://www.iss.net/security_center/advice/Exploits/Ports/
http://www.governmentsecurity.org/articles/CommonPorts.php

"Jodie" <jodie.fearon@cesjm.com> wrote in message
news:%23rg8LGx%23DHA.4012@tk2msftngp13.phx.gbl...
> I have an NT Server running firewall on my network to allow shared LAN
> access to the internet. I want to be able to prevent downloads and uploads
> EXCEPT from specified IP addresses.
>
> I would also like to block MSN Messenger and Yahoo instant messenger unless
> from specified IP addresses.
>
> I want to allow HTTP only from most IP addresses and block MSN Messenger,
> Yahoo Messenger, WinMX, Kazaa and all other common internet file sharing
> systems.
>
> My firewall allows my to do packet filtering based on protocols and their
> port numbers. Can anyone tell me what are the common port numbers for these
> applications or know where I can find that information? I now the general
> number for HTTP, FTP etc. but I do not know what port number WinMx and the
> others use.
>
> Thanks.
>
>

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