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Date:      Fri, 03 Dec 1999 18:04:19 +0000
From:      Adam Laurie <adam@algroup.co.uk>
To:        "Rodney W. Grimes" <freebsd@gndrsh.dnsmgr.net>
Cc:        Nate Williams <nate@mt.sri.com>, John Baldwin <jhb@FreeBSD.ORG>, freebsd-security@FreeBSD.ORG
Subject:   Re: rc.firewall revisited
Message-ID:  <38480623.518D798D@algroup.co.uk>
References:  <199912031748.JAA77378@gndrsh.dnsmgr.net>

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"Rodney W. Grimes" wrote:
> 
> > Nate Williams wrote:
> >
> > > >
> > > > And, of course, it also means you are wide open to attack from a
> > > > compromised name server. I do not want to trust hosts. I want to trust
> > > > specific connections to specific services.
> > >
> > > How do you propose to stop a compromised name server from giving out
> > > bogus information using a firewall rule?  I'm curious...
> >
> > Please re-read my statement. Who said anything about bogus information?
> > I'm talking about connecting to UDP ports (like NFS) that you're not
> > supposed to be able to connect to. Since his rule passes UDP that is
> > sourced from port 53 on the nameserver to ANY UDP port on ANY machine,
> > you are wide open to *attack*, not misinformation. At some point, your
> > chain of name servers has to talk to the outside world, so this means
> > the machine that does the final relay is open to attack from the outside
> > world.
> 
> Some one hand Adam a pair of wire cutters, that is the only way he is
> going to get the firewall he wants.

No, that is precicely my point. My set of rules allows DNS, but blocks
attacks. Just try it!

cheers,
Adam
--
Adam Laurie                   Tel: +44 (181) 742 0755
A.L. Digital Ltd.             Fax: +44 (181) 742 5995
Voysey House                  
Barley Mow Passage            http://www.aldigital.co.uk
London W4 4GB                 mailto:adam@algroup.co.uk
UNITED KINGDOM                PGP key on keyservers


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