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Build of NSD server
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The version of NSD used by this Dockerfile is the same as the one from the stable debian package nsd3. Currently, the version is 3.2.12.

What is NSD?

NSD is an authoritative only and open source DNS server. It is developed by NLnet Labs and it is distributed under the BSD license.

NSD website

wikipedia.org/wiki/NSD

How to use this image

Testing with an empty NSD server

By default, this image provides a NSD server with no configuration and no zone. It may still be tested by running on the host:

docker run -d --name nsd-server meseira/nsd

To interrogate this local empty name server, simply use dig:

dig @`docker inspect --format "{{ .NetworkSettings.IPAddress }}" nsd-server`

This command should return an empty QUESTION SECTION and some details about the request.

If you receive no response from the NSD server and an error message "connection timed out; no servers could be reached", this may be due to an input blockage from your firewall. In such a case, check the rules related to the docker0 interface.

Accessing the data

Two volumes devoted to handle the mutable data are included in the image. An easy way to deal with them consists in running /bin/bash in a container that can see them,

docker run -it --name nsd-data --hostname nsd-data \
               --volumes-from nsd-server \
               debian:wheezy /bin/bash

Thus, the log file nsd.log is located in /var/log/nsd,

root@nsd-data:/# cat /var/log/nsd/nsd.log

and the configuration and zone files are in /etc/nsd3,

root@nsd-data:/# ls /etc/nsd3

Adding configuration and zone files

For the moment, the container nsd-server is empty and does not serve to anything. Now we want to have fun with our own configuration and zone files.

The default configuration file is nsd.conf and is located in /etc/nsd3. Help about this file can be found with man 5 nsd.conf and in the sample configuration file,

root@nsd-data:/# cat /etc/nsd3/nsd.conf.sample

Let us take a basic example to test our server,

root@nsd-data:/# cat <<EOF > /etc/nsd3/nsd.conf
server:
  hide-version: yes
  identity: ""

zone:
  name: test.nsd
  zonefile: test.nsd.zone
EOF

The zone files can also be located in /etc/nsd3. The format of a zone file is defined in RFC 1035 (section 5) and RFC 1034 (section 3.6.1). For more details, see

wikipedia.org/wiki/Zone_file

In our example of nsd.conf, we have declared a zone test.nsd defined in a zone file test.nsd.zone. Let us create it,

root@nsd-data:/# cat <<EOF > /etc/nsd3/test.nsd.zone
\$ORIGIN test.nsd.
\$TTL 86400

@ IN SOA test.nsd. admin.test.nsd. (
    201410292335 ;
    28800 ;
    28800 ;
    864000 ;
    28800 ;
)

@ IN A 1.2.3.4
EOF

To take into account the changes, simply restart the container of the NSD server from the host,

docker restart nsd-server

You can use docker logs nsd-server to make sure there was no error and, if everything works, you can test the NSD server,

dig @`docker inspect --format "{{ .NetworkSettings.IPAddress }}" nsd-server` A test.nsd

You should obtain

[...]

;; QUESTION SECTION:
;test.nsd.    IN    A

;; ANSWER SECTION:
test.nsd.    86400    IN    A    1.2.3.4

[...]

Exposing the port

To use the container as a name server listening on the standard domain port of the host, we need to map its port 53/udp to the one of the host:

docker run -p 53:53/udp -d --name nsd-server nsd-server

Advanced configuration

Dealing with the configuration, log and zone files through the volumes given by the NSD server can be annoying. A better approach to handle these files is to proceed in the other way: create a container for the mutable data and share the volumes with the container of the NSD server. For this, we propose to use a host directory for the configuration and zones files, /nsd-conf in the sequel, and a simple volume for the logs. Thus, we create the container nsd-data with

docker run -it --name nsd-data --hostname nsd-data \
       -v /nsd-conf:/etc/nsd3 \
       -v /var/log/nsd \
       debian:wheezy /bin/bash

The host directory /nsd-conf contains your configuration and zone files and is mounted as a data volume on /etc/nsd3. Moreover, a classical volume is mounted on /var/log/nsd for the logs.

It is now simple to use this two volumes to create the container for the NSD server,

docker run -d -p 53:53/udp --name nsd-server \
       --volumes-from nsd-data \
       meseira/nsd

As above, if you modify a file in /nsd-conf (or in the directory /etc/nsd3 of the container /nsd-data), it is sufficient to restart the container nsd-server for taking it into account,

docker restart nsd-server

Issues

If you encounter any problem with this image, do not hesitate to report it in a GitHub issue.

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