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Date:      Wed, 3 Nov 1999 11:40:39 -0800 (PST)
From:      Matthew Dillon <dillon@apollo.backplane.com>
To:        "Juan Lorenzana" <lorenzaj@agcs.com>
Cc:        hackers@FreeBSD.ORG, freebsd-questions@FreeBSD.ORG, lorenzaj@agcs.com
Subject:   Re: nfs cookie spoofing patch
Message-ID:  <199911031940.LAA61182@apollo.backplane.com>
References:   <38208DDC.297EE98B@agcs.com>

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:I was wondering if I could get some help.
:
:I am running a FreeBSD 2.2.8 machine configured as a nfs server.  We are
:trying to get another machine running 2.2.8 to mount from the nfs
:server.  Our challenge is that we are using a virtual ip and would like
:to mount the virtual ip.  We are already doing this with SCO unix as
:well as Sun Solaris.  The problem is that when I type
:
:mount -t argonnfs:/u /u
:(I have also tried with -o -i,-s,-r=1024,-w=1024 options and all
:permutation of the options, including mount_nfs -T)
:
:I'll hang waiting for the request to time out.  After extensive trouble
:shooting, I think it is because of the "security feature" to prevent NFS
:cookie spoofing based attacks.  Basically, there is an nfs check that
:will not allow freebsd nfs client to request an nfs mount and have the
:machine where the nfs request is being made to reply with its real ip

    The problem is due to the NFS server responding to the NFS client's
    request using a different IP address.  The NFS client is expecting the
    response from the same IP that it sent the request too.

    The bug is on the server-side, not really the client side.  Many people
    have been bitten by this problem and it would be cool if someone submitted
    a patch to fix it.  I will get to it eventually but I'm kinda tied up
    at the moment.

    It would be a severe security hole to allow the client to process 
    responses from a different IP address then the request was sent to.

						-Matt



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