RE: DNS help

From: larosa, vjay (larosa_vjayat_private)
Date: Thu Dec 12 2002 - 11:54:29 PST

  • Next message: Valdis.Kletnieksat_private: "Re: DNS help"

    That is exactly what I am trying to figure out. What is the meaning
    of '[1au][|domain]'. 56162 is the DNS transaction ID. When a DNS server
    makes a request a number is tagged to it, that way when the reply comes
    back it can match it up with the request. I just don't know what the meaning
    of 1au is.
    
    vjl
    
    -----Original Message-----
    From: Valdis.Kletnieksat_private [mailto:Valdis.Kletnieksat_private]
    Sent: Thursday, December 12, 2002 12:18 PM
    To: larosa, vjay
    Cc: incidentsat_private
    Subject: Re: DNS help 
    
    
    On Wed, 11 Dec 2002 16:09:49 EST, "larosa, vjay" <larosa_vjayat_private>
    said:
    > Hello,
    > 
    > These packets were caught using a shadow IDS sensor. I was hoping that
    > somebody
    > in the list could help me understand what is happening below. I am
    familiar
    > with snort
    > and tcpdump, as well as the concept of packet fragmentation. I am mostly
    > interested in
    > finding out about the DNS requests being made, and why they are coming
    back
    > fragmented.
    
    Given that they fragged at 1480, I'd suspect you're going through a VPN
    at some point.  You're going to their nameserver to look something up
    and the replies are gettng fragged on the way.
    
    Is your DNS server a secondary for a zone hosted at outside.guy.com?  This
    looks like it might be AXFR traffic.  It's hard to tell without knowing what
    IDS produced the log entries - if I knew what '56162 [1au][|domain]' meant
    I could tell you more.
    
    > 12:15:24.020319 DNS.server.com.33795 > outside.guy.com.domain:  56162
    > [1au][|domain] (DF)
    
    > 12:15:24.170988 outside.guy.com.domain > DNS.server.com.33795:
    > 56162[|domain] (frag 48818:1480@0+)
    
    
    -- 
    				Valdis Kletnieks
    				Computer Systems Senior Engineer
    				Virginia Tech
    
    
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