Martin Zobel-Helas: Setting up GeoDNS for security.debian.org

Martin Zobel-Helas
Wed, 01 Jan 2014 15:48:08 +0000

DSA is currently playing around with a patched version of bind9 (based on a patch we received from kernel.org people) to implement GeoDNS for security.debian.org. You might have noticed that we currently have a round robin list of up to seven hosts in the security.debian.org rotation. Depending on time and luck your apt currently might pick a host which is located half around the globe for you, resulting in sometimes really slow download rates.

Idea

The current idea is to only present a list of security mirrors to you which are located on the continent you live on. We are aware that this won't work for all continents at the moment. For this reason we are also currently moving machines around the globe.

How to test

The easiest way for you to test is using bind9's dig command.

When trying from Germany one should get:

zobel@lunar:~% dig -ttxt +short security.geo.debian.org
"Europe view"

When trying from US one should get:

zobel@gluck:~% dig -ttxt +short security.geo.debian.org
"North America view"

Technique

The patch we used for bind9 uses libgeoip and MaxMind's GeoLite Country database. This patch was necessary to get bind to play nicely.

As we don't want to break security.debian.org at this stage of our testing, we decided to add a new subdomain security.geo.debian.org with which we are currently playing.

Having an ACL for EU defining all the countries belonging to the European Subcontinent, a config sniplet for security.debian.org's zone looks like this:

// Europe
acl EU {
        country_AD;
        country_AL;
        country_AT;
        country_AX;
        country_BA;
        country_BE;
        country_BG;
        country_BY;
        country_CH;
        country_CZ;
        country_DE;
        country_DK;
        country_EE;
        country_ES;
        country_FI;
        country_FO;
    ...
}

view "EU" {
        match-clients {
                EU;
        };
        zone "security.geo.debian.org" {
                type master;
                file "/etc/bind/zones/security.debian.org.EU.zone";
                notify no;
        };
};

To be sure we don't miss any contries, we added an additional view default, to catch what we didn't catch with the country codes:

view "other" {
        match-clients { any; };
        zone "security.geo.debian.org" {
                type master;
                file "/etc/bind/db.security.debian.org";
                notify no;
        };
};