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Friday, May 29, 2009

Configuring DNS servers on Ubuntu and Fedora

Just been setting up new DNS servers on my internal network. The primary was set up on an Ubuntu (Jackalope) system and the secondary on a Fedora Core 9. Both used Bind9 - the Ubuntu server had Bind 9.5.0-P2 and Fedora had 9.4.0.

On Ubuntu I followed the instructions in this Ubuntu guide and all went smoothly. I could test out the primary server and verify that it was working.

I figured the Fedora setup would be similar - but no - VERY different. For a start the Fedora configuration runs chroot around bind (I think that's the correct description) in order to make it more secure. So you have to put your files in /var/named/chroot/etc and /var/named/chroot/var/named (with symlinks from /etc/ in some cases).

The named.conf file format is a lot more involved under Fedora. You really want to use the samples in /usr/share/doc/bind-9.4.0/sample as a starting point. In particular, you need to put your zones in 'views' in the file.

Another problem I ran into was the need for a named.root file which contains the root servers for the Internet. You have to get this yourself and put it into /var/named/chroot/var/named/named.root.
# wget ftp://ftp.rs.internic.net/domain/named.root

And you need to have a file that tells DNS where this file is! (/var/named/chroot/etc/named.root.hints)

After doing all of that (and more) and trying to restart named it crapped out with these lines in /var/log/messages:
May 29 10:17:11 sequence named[12880]: starting BIND 9.4.0 -u named -t /var/named/chroot
May 29 10:17:11 sequence named[12880]: found 2 CPUs, using 2 worker threads
May 29 10:17:11 sequence named[12880]: loading configuration from '/etc/named.conf'
May 29 10:17:11 sequence named[12880]: /etc/named.rfc1912.zones:10: zone '.': already exists previous definition: /etc/nam
May 29 10:17:11 sequence named[12880]: listening on IPv4 interface lo,
May 29 10:17:11 sequence named[12880]: listening on IPv4 interface eth0,
May 29 10:17:11 sequence named[12880]: view.c:625: REQUIRE(view->hints == ((void *)0)) failed
May 29 10:17:11 sequence named[12880]: exiting (due to assertion failure)

Now what?! Thanks to this blog post I was able to comment out the '.' zone in the /var/named/chroot/etc/named.rfc1912.zones file, which is the duplication reported in the errors.

Finally I've got the secondary server up and running and getting my zones from the primary server. It just shouldn't be this difficult...



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