Re: waiting on sbwait

From: Don Lewis (truckman_at_FreeBSD.org)
Date: 06/25/04

  • Next message: Ivan Voras: "PF_PACKET" 
    Date: Fri, 25 Jun 2004 11:39:38 -0700 (PDT)
To: danny@cs.huji.ac.il

    On 24 Jun, Danny Braniss wrote:

    > found the cause: NFS/amd
    > a user had several symlinks to /net/host/xyz, and host was down.
    > doing ls -F /net/host/xyz does the trick, the machine becomes
    > unresponsive.

    /net is evil. A fun trick is to attempt to access
    /net/nonexistenthost and watch amd wedge while it gropes around the DNS
    tree looking for nonexistenthost. At a previous job I stumbled across
    this when I noticed that amd would hang whenever we lost our internet
    connection. Watching DNS queries sent to the Internet revealed all
    sorts of interesting things that could be considered to be a leak of
    sensitive information.

    I also don't like NFS exporting /, and accessing /net/machine doesn't
    work too well if / isn't exported.
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