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List:       freebsd-hackers
Subject:    Re: waiting on sbwait
From:       Don Lewis <truckman () freebsd ! org>
Date:       2004-06-25 18:39:38
Message-ID: 200406251839.i5PIdcTV060752 () gw ! catspoiler ! org
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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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