nanog mailing list archives
RE: How to track DNS resolution sources
From: teleric team <teleric-lists () outlook com>
Date: Wed, 3 Dec 2014 12:24:33 -0500
Date: Wed, 3 Dec 2014 17:56:23 +0100 From: bortzmeyer () nic fr To: notify.sina () gmail com Subject: Re: How to track DNS resolution sources CC: nanog () nanog org On Wed, Dec 03, 2014 at 05:22:58PM +0100, Notify Me <notify.sina () gmail com> wrote a message of 13 lines which said:I hope I'm wording this correctly.Not really :-)I had a incident at a client site where a DNS record was being spoofed.How do you know? What steps did you use to assert this? Answers to these questions would help to understand your problem.How does one track down the IP address that's returning the false records ?If it's real DNS spoofing (which I doubt), the source IP address of the poisoner is forged, so it would not help. The main tool to use is dig. Let's assume the name that bothers you is foobar.example.com. Query your local resolver: dig A foobar.example.com Query an external resolver, here Google Public DNS: dig @8.8.4.4 A foobar.example.com Query the authoritative name servers of example.com. First, to find them: dig NS example.com Second, query them (replace the server name by the real one): dig @a.iana-servers.net. A foobar.example.com
I didn't understand how this will help him identify the poisoner. What an IDS rule will do is check for responding authoritative query IDs for DNS queries never made to that responder, but made for the authoritative server identified as per above (direct NS inquiry). If no IDS is present, BIND logging would allow for identification of authoritative responses and query ID identification. In summary whatever is answered authoritatively by a server other than the NS ones tracked by "dig +trace foobar.examplecom" is the potential poisoner. But if the poisoing is done from an spoofed IP address (spoofing the authoritative IP), well good luck w/ that if the spoofed domain is not DNSSEC aware.
Current thread:
- How to track DNS resolution sources Notify Me (Dec 03)
- Re: How to track DNS resolution sources TR Shaw (Dec 03)
- Re: How to track DNS resolution sources Stephane Bortzmeyer (Dec 03)
- Re: How to track DNS resolution sources Stephane Bortzmeyer (Dec 03)
- RE: How to track DNS resolution sources teleric team (Dec 03)
- Message not available
- Re: How to track DNS resolution sources Notify Me (Dec 04)
- Re: How to track DNS resolution sources TR Shaw (Dec 03)