Blocking ports

Discussion in 'A+ Certification' started by Nell, Sep 21, 2005.

  1. Nell

    Nell Guest

    Does anyone know which ports to block to prevent users from using chat
    / IRC groups use, like Yahoo, MSN Messenger and Windows Messenger?

    Thanks!
    Nell, Sep 21, 2005
    #1
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  2. Nell

    Jim Guest

    Jim, Sep 21, 2005
    #2
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  3. If you do a Google search for MSN messenger ports etc you will find the
    information OR do a little detective work on a computer that is running
    them. You can use the command netstat -an to see what ports a computer is
    using or better yet use a free tool like TCPView from SysInternals to see
    the port use. If your firewall has the capability it is best to start with a
    default deny all rule for outbound access and then define the authorized
    exceptions. Also keep in mind that a lot of chat programs will attempt to
    tunnel through port 80 TCP which is used for internet http and can make it
    difficult to stop unless you can find and block the IP addresses of the
    servers they tunnel to, use software firewalls that have application based
    rules like Zone Alarm, Sygate, Norton, etc. or use a gateway firewall device
    that can do advanced application filtering for http like Microsoft ISA
    004. --- Steve

    http://www.sysinternals.com/Utilities/TcpView.html


    "Nell" <> wrote in message
    news:...
    > Does anyone know which ports to block to prevent users from using chat
    > / IRC groups use, like Yahoo, MSN Messenger and Windows Messenger?
    >
    > Thanks!
    Steven L Umbach, Sep 22, 2005
    #3
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