DNS Server

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Contents

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Overview

This article describes how to install and configure DNS services on Ubuntu Server Edition.

Domain Name Service (DNS) is an Internet service that maps IP addresses and fully qualified domain names (FQDN) to one another. In this way, DNS alleviates the need to remember IP addresses. Computers that run DNS are called name servers. Ubuntu ships with BIND9 (Berkley Internet Naming Daemon), the most common program used for maintaining a name server on GNU/Linux.


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Installation

At the terminal type the following command to install BIND9 DNS server. 

sudo apt-get install bind9


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Configuration

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Configure Server Host Name and Domain

Check that your servers host name and domain are configured correctly. 

sudo nano /etc/hosts

Run the following command to test. 

hostname -f


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Configure bind9 for Secure Chroot 

sudo /etc/init.d/bind9 stop
sudo nano /etc/default/bind9

Change:
OPTIONS="-u bind"
TO:
OPTIONS="-u bind -t /var/lib/named"

Configure Internet Name Resolution Forwarders

Your internal DNS server will resolve internal computer names and IP addresses. External names should be resolved by DNS servers on the internet. The following allows your internal DNS server to forward unknown name request to your ISP's DNS servers. Substitute the below addresses with your ISP's DNS server addresses. 

sudo nano /etc/bind/named.conf.options

forwarders {
     205.171.3.65;
     205.171.2.65;
};


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Setup Chroot Jail

Chroot helps keep your bind9 DNS server secure. The following commands can be cut and pasted into your terminal - one at a time. 

sudo mkdir -p /var/lib/named/etc
sudo mkdir /var/lib/named/dev
sudo mkdir -p /var/lib/named/var/cache/bind
sudo mkdir -p /var/lib/named/var/run/bind/run
sudo mv /etc/bind /var/lib/named/etc
sudo ln -s /var/lib/named/etc/bind /etc/bind
sudo mknod /var/lib/named/dev/null c 1 3
sudo mknod /var/lib/named/dev/random c 1 8
sudo chmod 666 /var/lib/named/dev/*
sudo chown -R bind:bind /var/lib/named/var/*
sudo chown -R bind:bind /var/lib/named/etc/bind

sudo nano /etc/init.d/sysklogd

Change:
SYSLOGD="-u syslog"
TO:
SYSLOGD="-a /var/lib/named/dev/log"

sudo nano /etc/resolv.conf

Remove current lines and replace with:

search mydomain.lan nameserver 127.0.0.1 

sudo /etc/init.d/sysklogd restart
sudo /etc/init.d/bind9 start

Test: 

ping www.google.com


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Setup our Internal Network Zones

Setup our Internal Network Zones 

sudo mkdir /etc/bind/zones/
sudo nano /etc/bind/zones/master_mydomain.lan

Example file. Modify for your needs. 

$TTL 3D

@       IN      SOA     thisserver.mydomain.lan. hostmaster.mydomain.lan. (
                        200611251       ; serial, todays date + todays serial #
                        8H              ; refresh, seconds
                        2H              ; retry, seconds
                        4W              ; expire, seconds
                        1D )            ; minimum, seconds
;
                TXT     "MyDomain.LAN, serving YOUR domain :)"
                NS      thisserver       ; Inet Address of name server
;               MX      10 mail        ; Primary Mail Exchanger
localhost    A    127.0.0.1
thisserver    A   10.10.1.1


Configure Bind9 to Use Your New Network Zone 

sudo nano /etc/bind/named.conf.local

zone "mydomain.lan" {
        type master;
        file "/etc/bind/zones/master_mydomain.lan";
};


Restart the Bind9 Service 

sudo /etc/init.d/bind9 start

Test

ping thisserver.mydomain.lan from another computer

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