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Date:      Fri, 04 May 2001 01:30:47 -0300
From:      "lists@mail.ru" <lists@mail.ru>
To:        freebsd-security@freebsd.org
Subject:   Re: reverse or not
Message-ID:  <3AF23077.55DEA3D8@mail.ru>
References:  <5.0.2.1.2.20010503145244.00a12e50@nol.co.za> <Pine.BSF.4.30.0105031358300.26752-100000@R181204.resnet.ucsb.edu> <20010503170027.B9233@tjhsst.edu> <3AF1DC23.32BB39B3@globalstar.com>

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Crist Clark wrote:
> 
> Andrew Barros wrote:
> >
> > I've had similar problems with sshd when my internet connection goes out.
> >
> > If you try to ssh into that machine, it takes _forever_ even if the local
> > nameserver is running.
When the SSH server accepts a connection it does a reverse lookup the
client's IP
address. If that IP address is not in your named configuration, the
named
will try to resolve it as usual in DNS queries, using other DNS servers.
If the link is down, the SSH will return from the reverse lookup when
the
timeout of the reverse lookup expires.


> 
> Just because named is running does not mean DNS is configured correctly. ;)
> 
> Run a tcpdump on the external interface to see if there are still queries
> going out for some reason, and you are waiting for them to timeout. Run ssh
> with the '-v' option to see where things are hanging. Possibly try sshd with
> '-d' as well.
> --
> Crist J. Clark                                Network Security Engineer
> crist.clark@globalstar.com                    Globalstar, L.P.
> (408) 933-4387                                FAX: (408) 933-4926
> 
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Why don't you check if reverse lookups are resolved by your
nameserver?
Try it using "nslookup 127.0.0.1 127.0.0.1".
If you are not resolving reverse queries for 127.0.0.1,
nobody will do it and then the timeout will happen.

-
Agustin Azubel Friedman - aazubel@mail.ru

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