DNS DOS increasing?

Curtis Maurand curtis at canon.maurand.com
Mon Jan 21 19:44:48 UTC 2002


I'm not seeing this behavior with RH 7.2 128MB and bind 9.n

---- Original Message ----
From:		Karyn Ulriksen
Date:		Mon 1/21/02 11:49
To:		LIST, NANOG
Subject:	RE: DNS DOS increasing?

RE: DNS DOS increasing?I've seen this behavior before, also.  I thought it
was interesting that two servers side by side recieving the same
attacks/ratios only serving DNS (BIND 8.2.x*) and  acted in this manner:

        Redhat 6.2 w/dual proc 833 512/ram    started "loosing" RR records
        Solaris 7 on a Sparc 10 (hehe) w/256    rebooted and served the
correct records

I'm curious to see how other OSes react to these attacks.  My guess is that
BSD systems (such as FreeBSD and BSDi) will react similarly to the Solaris
based on my past experience with these systems.  So I am curious too see if
the RR record "loss" is an OS specific behaviour, especially since Redhat
has priors in misplacing information in earlier versions of the OS.

* I say BIND 8.2.x, because this continued to occur through the various BIND
8.2 releases.

Best regards,

Karyn Ulriksen
Valkaryn Internet Group
URL: http://www.valkaryn.net
email:  valkaryn at valkaryn.net
===========================================
"Decisions should be made in the space of seven breaths."


  -----Original Message-----
  From: Karyn Ulriksen [mailto:valkaryn at valkaryn.net]
  Sent: Monday, January 21, 2002 8:39 AM
  To: James Smith
  Subject: RE: DNS DOS increasing?


  I've seen this behavior before, also.  I thought it was interesting that
two servers side by side recieving the same attacks/ratios only serving DNS
(BIND 8.2.x*) and  acted in this manner:

          Redhat 6.2 w/dual proc 833 512/ram    started "loosing" RR records
          Solaris 7 on a Sparc 10 (hehe) w/256    rebooted and served the
correct records

  I'm curious to see how other OSes react to these attacks.  My guess is
that BSD systems (such as FreeBSD and BSDi) will react similarly to the
Solaris based on my past experience with these systems.  So I am curious too
see if the RR record "loss" is an OS specific behaviour, especially since
Redhat has priors in misplacing information in earlier versions of the OS.

  * I say BIND 8.2.x, because this continued to occur through the various
BIND 8.2 releases.

  Best regards,

  Karyn Ulriksen
  Valkaryn Internet Group
  URL: http://www.valkaryn.net
  email:  valkaryn at valkaryn.net
  ===========================================
  "Decisions should be made in the space of seven breaths."


    -----Original Message-----
    From: owner-nanog at merit.edu [mailto:owner-nanog at merit.edu]On Behalf Of
James Smith
    Sent: Monday, January 21, 2002 7:08 AM
    To: nanog at merit.edu
    Subject: RE: DNS DOS increasing?


     I've seen DOS-type behavior where a client will query a resolver for a
     name that doesn't exist, and the client does not accept the answer that
     the name does not exist and immediately sends another query, regardless
     of whether or not the resolver declared itself authoritative for the
     negative answer.

    --
    /ak

      Get ready for more DOS-like behavior as systems get deployed that have
10 second TTLs in the DNS. These systems are used to provide multi-isp
redundancy by pinging each upstreams router, and when a ping fails, start
giving out a dns response using the other ISP IP range. Same FQDN, new IP.

      This of course is driven by the desire for redundancy in small
businesses who make the Internet an integral part of their business plan.
Either they can't get PI space and don't have (or don't want to spend) the
$$$ to do BGP, or are unable to convince their upstream to cut a hole in
their CIDR block and allow a 2nd party to announce that chunk (which for
some is as small as /28).

    James H. Smith II  NNCDS NNCSE
    Systems Engineer
    The Presidio Corporation





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