nanog mailing list archives
Re: Open Resolver Problems
From: Jon Lewis <jlewis () lewis org>
Date: Tue, 26 Mar 2013 10:15:54 -0400 (EDT)
On 25/03/2013 14:33, Mikael Abrahamsson wrote:I would like to be able to request an IP list of open resolvers in my ASN, perhaps sent to the contact details in RIPE whois database to make sure I'm not falsely representing that ASN.
Or you could just get an off-site system (cloud VM), get the software from http://monkey.org/~provos/dnsscan/, and find all your own open recursive DNS servers.
There are different levels of openness for recursive DNS servers though. It looks like Jared's project lists any DNS server that responds with anything other than refused as open. A DNS server could have open recursion "disabled", but still respond with referrals to the root-servers. Older versions of bind seem to do this when configured with allow-recursion for a limited range of IPs. While not really "open" such servers are still useful for DNS amplification. The example config at
http://www.team-cymru.org/Services/Resolvers/instructions.htmlfor a bind 9.x caching server can be adapted for older bind versions doing caching+authoratative such that it'll provide recursion to those who should have it, and authority for zones for which it needs to do so.
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Current thread:
- Re: Open Resolver Problems, (continued)
- Re: Open Resolver Problems Joe Abley (Mar 25)
- Re: Open Resolver Problems Mikael Abrahamsson (Mar 25)
- Re: Open Resolver Problems Nick Hilliard (Mar 25)
- Re: Open Resolver Problems Alain Hebert (Mar 25)
- Re: Open Resolver Problems William Herrin (Mar 25)
- Re: Open Resolver Problems Nick Hilliard (Mar 25)
- Re: Open Resolver Problems William Herrin (Mar 25)
- Re: Open Resolver Problems Jay Ashworth (Mar 26)
- Re: Open Resolver Problems Mikael Abrahamsson (Mar 26)
- Re: Open Resolver Problems Jared Mauch (Mar 25)
- Re: Open Resolver Problems Jon Lewis (Mar 26)
- Re: Open Resolver Problems Jared Mauch (Mar 26)
- Re: Open Resolver Problems Jared Mauch (Mar 25)
- RE: Open Resolver Problems Mike Simkins (Mar 25)
- Re: Open Resolver Problems Damian Menscher (Mar 25)
- Re: Open Resolver Problems Jared Mauch (Mar 25)
- Re: Open Resolver Problems Alain Hebert (Mar 25)
- Re: Open Resolver Problems Mark Andrews (Mar 25)