Overwrite A record from DNSSEC protected domain if I am the owner of the domain

Thu Apr 27 00:57:00 UTC 2017

What you are describing more generally sounds like what is known as split-view or split-horizon DNS. In short, you split all (or part by virtue of delegation or forwarders) of your namespace into “internal” and “external” partitions; this is documented in the context of BIND here: https://ftp.isc.org/isc/bind9/cur/9.10/doc/arm/Bv9ARM.ch04.html#split_dns

Best practices for DNSSEC under split-view vary, but several approaches along with their strengths and weakness are documented in this RFC draft:
https://tools.ietf.org/html/draft-krishnaswamy-dnsop-dnssec-split-view-04

We have been using 4.1.2 in production for the last year or so… it works very well, but as the draft suggests there is a high overhead in the management of the keys, zones, and views, especially if you have a large namespace.

4.1.5 may be an easier option if you are a small shop and trust your internal networks.

Cheers,

Mathew Eis
Northern Arizona University
Information Technology Services

-----Original Message-----
From: bind-users <bind-users-bounces at lists.isc.org> on behalf of Matthias Fechner <idefix at fechner.net>
Date: Wednesday, April 26, 2017 at 9:36 AM
To: "bind-users at lists.isc.org" <bind-users at lists.isc.org>
Subject: Overwrite A record from DNSSEC protected domain if I am the owner of the domain

    Dear all,

    I have a domain fechner.net which is protected using DNSSEC.

    The zone is managed on a server located in a data center.

    Some A records are pointing to a computer that has a low speed internet 
    connection on the WAN site, but very fast connection on the LAN site.

    If I know located in this LAN and I resolve the hostname (in this LAN 
    also bind9.10 is running), I will get the IP of the WAN connection and 
    the traffic is flowing out of the interface where the standard gateway 
    is defined, goes to the provider and is coming back over a tunnel using 
    the WAN connection. I can explain it more in detail, but the routing 
    should not be important for the question I have.

    Now I would like to overwrite some of the A records from my zone (I have 
    full access to public and private key for DNSSEC).
    Some CNAMEs will point to this A record, so I have to change only the IP 
    from the A record, all other CNAMEs can be handled by the offical bind 
    that it reachable on the internet.

    Normally I would use RPZ to handle this, but it seems that this will not 
    work if the A record is using DNSSEC (at least the manual says that it 
    will not rewrite the A record if DNSSEC is used to protect the A record).

    So what I would like to have:
    - if I resolve from external it should reolve to the official IP that is 
    reachable from the internet
    - if I resolve from my local LAN it should return the internal IP like 
    192.168.0.1, that is only reachable from the LAN

    What is the suggested (best practise) approach to handle such a case 
    with bind 9.10?

    Thanks a lot.

    Gruß
    Matthias

    -- 

    "Programming today is a race between software engineers striving to
    build bigger and better idiot-proof programs, and the universe trying to
    produce bigger and better idiots. So far, the universe is winning." --
    Rich Cook

    _______________________________________________
    Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list

    bind-users mailing list
    bind-users at lists.isc.org
    https://lists.isc.org/mailman/listinfo/bind-users