Re: ICMP Ping and Group Policy Update

From: Paul Robichaux (paul_at_ROBICHAUX.NET)
Date: 10/01/03

  • Next message: Ken Hoover: "Re: ICMP Ping and Group Policy Update"
    Date:         Wed, 1 Oct 2003 10:13:21 -0400
    To: NTBUGTRAQ@LISTSERV.NTBUGTRAQ.COM
    
    

    Block ICMP packets with length 92 and you're golden. Blocking all ICMP
    causes other problems, as you note; it's equivalent to blocking all, say,
    TCP trafffic in that it improves your security while degrading your
    functionality.

    > From: Information Security <InformationSecurity@FEDERATEDINV.COM>
    > Reply-To: Windows NTBugtraq Mailing List <NTBUGTRAQ@LISTSERV.NTBUGTRAQ.COM>
    > Date: Tue, 30 Sep 2003 11:00:54 -0400
    > To: NTBUGTRAQ@LISTSERV.NTBUGTRAQ.COM
    > Subject: ICMP Ping and Group Policy Update
    >
    > In response to Nachi, we blocked ICMP Pings to & from our VPN. However,
    > it appears that this also has disabled group policy updates for remote
    > VPN users. We ran network traces and saw the ICMP packets, I think
    > they're part of the negotiation phase where the server tries to
    > determine if the client is on a slow link.
    >
    > I suspect a lot of networks cranked down on ICMP after Nachi. Can
    > anyone else confirm this behavior? Does anyone have a workaround or
    > configuration setting to override/bypass this feature?
    >
    > Thanks!
    >
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  • Next message: Ken Hoover: "Re: ICMP Ping and Group Policy Update"

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