In this article, you will learn how easy and quick it is to have your caching resolving DNS Server (unbound), as well as an authoritative/master DNS Server (NSD) running locally on your own OpenBSD AKLWEB HOST Instance.

While NSD was available in previous releases too, unbound was linked to the build for the 5.6 release. Starting with the 5.7 release, BIND will be completely removed from the base system (and available via ports).

unbound

For resolving DNS, people generally use defaults provided by their distribution/provider or a service from Google (public DNS) and OpenDNS. While those are usually fine, running your own gives you more control, better performance (once you fill out your own cache), better privacy, etc. It is very easy to get your own DNS setup on OpenBSD.

Enable the service:

sudo rcctl enable unbound

Start the service:

sudo rcctl start unbound

To make it active, put the following in /etc/resolv.conf (and delete any other nameserver entries): 

nameserver 127.0.0.1

You can now try it out:

dig google.com

We’re looking for the following two lines:

;; Query time: 35 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)

The server used was localhost, which is what we wanted. Query time is 35 seconds on a cold start. Let’s try the same dig command one more time:

;; Query time: 1 msec

At this point, the caching is working, and we can continue with the authoritative NSD Server.

NSD

Unlike unbound, NSD is an authoritative DNS Server, which is used for serving your own zones. One server is generally not enough, so you could spin up another AKLWEB HOST Instance as a secondary server in another location, for redundancy.

Since setting up primary/secondary service (although not hard) is a bit out of the scope of this article, we will show how to serve a single domain zone.

First, let’s edit the /var/nsd/etc/nsd.conf file. Here is a complete example:

server:
   hide-version: yes
   ip-address: 108.xx.xxx.xx

remote-control:
   control-enable: yes

zone:
   name: "example.com"
   zonefile: "example.com.zone"

Note: Replace 108.xx.xxx.xx with the IP address of your instance and example.com with your domain.

Zone files go to /var/nsd/zones directory. Here is a short /var/nsd/zones/example.com.zone zone file:

$ORIGIN example.com.
$TTL 86400

@       3600    SOA     a.ns.example.com. hostmaster.example.com. (
                       2014110502      ; serial
                       1800            ; refresh
                       7200            ; retry
                       1209600         ; expire
                       3600 )          ; negative

               NS      a.ns.example.com.
               NS      b.ns.example.com.

               MX      0 mail.example.com.

a.ns            A       108.xx.xxx.xx
b.ns            A       108.xx.xxx.xx
mail            A       108.xx.xxx.xx

We can now enable and start the service:

sudo rcctl enable nsd
sudo rcctl start nsd

You should now have both your caching/resolving DNS Server, as well as an authoritative one.

BIND zone syntax and details on running your own master are a bit out of the scope of this short guide and left as an exercise to the reader. Enjoy OpenBSD!