Step by Step tutorial guide to configure BIND DNS server in chroot environment for Red Hat (RHEL/CentOS) 7

This article is little outdated as with RHEL 7 now you do not need to copy the bind DNS configuration files into the chroot environment.

Step-by-Step Tutorial: Configure DNS Server using bind chroot (CentOS/RHEL 7)

In this article I will share the list of steps to configure DNS server on RHEL 7 or CentOS 7.

For the demonstration of the steps I have used Red Hat Enterprise Linux 7.4
Our aim to create one A record and one PTR record for forward and reverse lookup respectively.

Firstly install the required rpms to configure your DNS server

NOTE: On RHEL system you must have an active subscription to RHN or you can configure a local offline repository using which "yum" package manager can install the provided rpm and it's dependencies.

# yum install bind bind-chroot caching-nameserver

My setup details

# hostname
golinuxhub-client.example

My IP address is 192.168.1.7

# ip address | egrep 'inet.*enp0s3'
inet 192.168.1.7/24 brd 192.168.1.255 scope global dynamic enp0s3

Since we will be using chroot environment disable the below services

# systemctl stop named

# systemctl disable named

Next copy the required files inside chroot directory.

NOTE: Use -p argument along with cp command to preserve the permission and ownership of all the files and directories

[root@golinuxhub-client ~]# cp -rpvf /usr/share/doc/bind-9.9.4/sample/etc/* /var/named/chroot/etc/
‘/usr/share/doc/bind-9.9.4/sample/etc/named.conf’ -> ‘/var/named/chroot/etc/named.conf’
‘/usr/share/doc/bind-9.9.4/sample/etc/named.rfc1912.zones’ -> ‘/var/named/chroot/etc/named.rfc1912.zones’

Next copy the zone related files inside the new location

[root@golinuxhub-client ~]# cp -rpvf /usr/share/doc/bind-9.9.4/sample/var/named/* /var/named/chroot/var/named/
‘/usr/share/doc/bind-9.9.4/sample/var/named/data’ -> ‘/var/named/chroot/var/named/data’
‘/usr/share/doc/bind-9.9.4/sample/var/named/my.external.zone.db’ -> ‘/var/named/chroot/var/named/my.external.zone.db’
‘/usr/share/doc/bind-9.9.4/sample/var/named/my.internal.zone.db’ -> ‘/var/named/chroot/var/named/my.internal.zone.db’
‘/usr/share/doc/bind-9.9.4/sample/var/named/named.ca’ -> ‘/var/named/chroot/var/named/named.ca’
‘/usr/share/doc/bind-9.9.4/sample/var/named/named.empty’ -> ‘/var/named/chroot/var/named/named.empty’
‘/usr/share/doc/bind-9.9.4/sample/var/named/named.localhost’ -> ‘/var/named/chroot/var/named/named.localhost’
‘/usr/share/doc/bind-9.9.4/sample/var/named/named.loopback’ -> ‘/var/named/chroot/var/named/named.loopback’
‘/usr/share/doc/bind-9.9.4/sample/var/named/slaves’ -> ‘/var/named/chroot/var/named/slaves’
‘/usr/share/doc/bind-9.9.4/sample/var/named/slaves/my.ddns.internal.zone.db’ -> ‘/var/named/chroot/var/named/slaves/my.ddns.internal.zone.db’
‘/usr/share/doc/bind-9.9.4/sample/var/named/slaves/my.slave.internal.zone.db’ -> ‘/var/named/chroot/var/named/slaves/my.slave.internal.zone.db’

Lets start configuring our primary configuration file

# cd /var/named/chroot/etc/

Clear the existing named.conf and paste the below content

[root@golinuxhub-client etc]# vim named.conf
options {
listen-on port 53 { 127.0.0.1; any; };
# listen-on-v6 port 53 { ::1; };
directory "/var/named";
dump-file "/var/named/data/cache_dump.db";
statistics-file "/var/named/data/named_stats.txt";
memstatistics-file "/var/named/data/named_mem_stats.txt";
allow-query { localhost; any; };
allow-query-cache { localhost; any; };
};

logging {
channel default_debug {
file "data/named.run";
severity dynamic;
};
};

view my_resolver {
match-clients { localhost; any; };
recursion yes;
include "/etc/named.rfc1912.zones";
};

The zone related content information must be added in /var/named/chroot/etc/named.rfc1912.zones, append the below entries.

Here example.zone is our forward zone file while example.rzone is our reverse zone file for reverse lookup entry

IMPORTANT NOTE: The reverse lookup zone contains 1.168.192 because my host IP is 192.168.1.7

zone "example" IN {
type master;
file "example.zone";
allow-update { none; };
};

zone "1.168.192.in-addr.arpa" IN {
type master;
file "example.rzone";
allow-update { none; };
};

The zone related files are available under below path

# cd /var/named/chroot/var/named/

Next lets create our forward and reverse zone file, the filenames will be same as what we gave in our named.rfc1912.zones file above, we already have some default templates which we can use as below

# cp -p named.localhost example.zone
# cp -p named.loopback example.rzone

As you see the existing permission of all the files and directories are owned by root

[root@golinuxhub-client named]# ll
total 32
drwxr-xr-x. 2 root root 6 May 22 2017 data
-rw-r--r--. 1 root root 168 May 22 2017 example.rzone
-rw-r--r--. 1 root root 152 May 22 2017 example.zone
-rw-r--r--. 1 root root 56 May 22 2017 my.external.zone.db
-rw-r--r--. 1 root root 56 May 22 2017 my.internal.zone.db
-rw-r--r--. 1 root root 2281 May 22 2017 named.ca
-rw-r--r--. 1 root root 152 May 22 2017 named.empty
-rw-r--r--. 1 root root 152 May 22 2017 named.localhost
-rw-r--r--. 1 root root 168 May 22 2017 named.loopback
drwxr-xr-x. 2 root root 71 Feb 12 21:02 slaves

Change the permission of all the files under this location with root as user owner and named as the group owner

# chown root:named *

Although for the data partition the user and group owner must be 'named'

# chown -R named:named data

# ls -l
total 32
drwxr-xr-x. 2 named named 6 May 22 2017 data
-rw-r--r--. 1 root named 168 May 22 2017 example.rzone
-rw-r--r--. 1 root named 152 May 22 2017 example.zone
-rw-r--r--. 1 root named 56 May 22 2017 my.external.zone.db
-rw-r--r--. 1 root named 56 May 22 2017 my.internal.zone.db
-rw-r--r--. 1 root named 2281 May 22 2017 named.ca
-rw-r--r--. 1 root named 152 May 22 2017 named.empty
-rw-r--r--. 1 root named 152 May 22 2017 named.localhost
-rw-r--r--. 1 root named 168 May 22 2017 named.loopback
drwxr-xr-x. 2 root named 71 Feb 12 21:02 slaves

Append the below content for our forward zone file. Here we are creating A record for our localhost (golinuxhub-client) and one more for one of my server node (golinuxhub-server)

# vim example.zone
$TTL 1D
@ IN SOA example. root (
1 ; serial
3H ; refresh
15M ; retry
1W ; expire
1D ) ; minimum

IN NS example.

IN A 192.168.1.7
golinuxhub-server IN A 192.168.1.5
golinuxhub-client IN A 192.169.1.7

Append the below content for our reverse zone file. Here we are creating PTR record for our localhost and one more for one of my server node (golinuxhub-server)

# vim example.rzone
$TTL 1D
@ IN SOA example. root.example. (
1997022700 ; serial
28800 ; refresh
14400 ; retry
3600000 ; expire
86400 ) ; minimum

IN NS example.
5 IN PTR golinuxhub-server.example.
7 IN PTR golinuxhub-client.example.

Before we start our named-chroot service, we will validate the zone file configuration

[root@golinuxhub-client named]# named-checkzone golinuxhub-client.example example.zone
zone golinuxhub-client.example/IN: loaded serial 1
OK

[root@golinuxhub-client named]# named-checkzone golinuxhub-client.example example.rzone
zone golinuxhub-client.example/IN: loaded serial 1997022700
OK

All looks ok there, check the configuration file using below command

[root@golinuxhub-client named]# named-checkconf -t /var/named/chroot/ /etc/named.conf

So our command executed successfully

[root@golinuxhub-client named]# echo $?
0

IMPORTANT NOTE: For my setup SELinux is in permissive mode

# getenforce
Permissive

Everything looks fine so time to start our named-chroot service

[root@golinuxhub-client named]# systemctl restart named-chroot

[root@golinuxhub-client named]# systemctl status named-chroot
● named-chroot.service - Berkeley Internet Name Domain (DNS)
Loaded: loaded (/usr/lib/systemd/system/named-chroot.service; disabled; vendor preset: disabled)
Active: active (running) since Mon 2018-02-12 21:53:23 IST; 19s ago
Process: 5236 ExecStop=/bin/sh -c /usr/sbin/rndc stop > /dev/null 2>&1 || /bin/kill -TERM $MAINPID (code=exited, status=0/SUCCESS)
Process: 5327 ExecStart=/usr/sbin/named -u named -c ${NAMEDCONF} -t /var/named/chroot $OPTIONS (code=exited, status=0/SUCCESS)
Process: 5325 ExecStartPre=/bin/bash -c if [ ! "$DISABLE_ZONE_CHECKING" == "yes" ]; then /usr/sbin/named-checkconf -t /var/named/chroot -z "$NAMEDCONF"; else echo "Checking of zone files is disabled"; fi (code=exited, status=0/SUCCESS)
Main PID: 5330 (named)
CGroup: /system.slice/named-chroot.service
└─5330 /usr/sbin/named -u named -c /etc/named.conf -t /var/named/chroot

Feb 12 21:53:23 golinuxhub-client.example named[5330]: managed-keys-zone/my_resolver: loaded serial 0
Feb 12 21:53:23 golinuxhub-client.example named[5330]: zone 0.in-addr.arpa/IN/my_resolver: loaded serial 0
Feb 12 21:53:23 golinuxhub-client.example named[5330]: zone 1.0.0.127.in-addr.arpa/IN/my_resolver: loaded serial 0
Feb 12 21:53:23 golinuxhub-client.example named[5330]: zone 1.168.192.in-addr.arpa/IN/my_resolver: loaded serial 1997022700
Feb 12 21:53:23 golinuxhub-client.example named[5330]: zone example/IN/my_resolver: loaded serial 1
Feb 12 21:53:23 golinuxhub-client.example named[5330]: zone localhost/IN/my_resolver: loaded serial 0
Feb 12 21:53:23 golinuxhub-client.example named[5330]: zone 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa/IN/my_resolver: loaded serial 0
Feb 12 21:53:23 golinuxhub-client.example named[5330]: zone localhost.localdomain/IN/my_resolver: loaded serial 0
Feb 12 21:53:23 golinuxhub-client.example named[5330]: all zones loaded
Feb 12 21:53:23 golinuxhub-client.example named[5330]: running

Make sure your resolv.conf contains the IP of your setup so that it can act as a DNS server

# cat /etc/resolv.conf
search example
nameserver 192.168.1.7

Lets validate our DNS server for our reverse zone file using dig

[root@golinuxhub-client named]# dig -x 192.168.1.5

; <<>> DiG 9.9.4-RedHat-9.9.4-50.el7 <<>> -x 192.168.1.5
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 40331
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 2

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;5.1.168.192.in-addr.arpa. IN PTR

;; ANSWER SECTION:
5.1.168.192.in-addr.arpa. 86400 IN PTR golinuxhub-server.example.

;; AUTHORITY SECTION:
1.168.192.in-addr.arpa. 86400 IN NS example.

;; ADDITIONAL SECTION:
example. 86400 IN A 192.168.1.7

;; Query time: 1 msec
;; SERVER: 192.168.1.7#53(192.168.1.7)
;; WHEN: Mon Feb 12 22:13:17 IST 2018
;; MSG SIZE rcvd: 122

As you see we do get a positive response with a ANSWER for our QUERY

[root@golinuxhub-client named]# dig -x 192.168.1.7

; <<>> DiG 9.9.4-RedHat-9.9.4-50.el7 <<>> -x 192.168.1.7
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 55804
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 2

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;7.1.168.192.in-addr.arpa. IN PTR

;; ANSWER SECTION:
7.1.168.192.in-addr.arpa. 86400 IN PTR golinuxhub-client.example.

;; AUTHORITY SECTION:
1.168.192.in-addr.arpa. 86400 IN NS example.

;; ADDITIONAL SECTION:
example. 86400 IN A 192.168.1.7

;; Query time: 1 msec
;; SERVER: 192.168.1.7#53(192.168.1.7)
;; WHEN: Mon Feb 12 22:12:54 IST 2018
;; MSG SIZE rcvd: 122

Similarly we can validate our forward zone file

[root@golinuxhub-client named]# nslookup golinuxhub-client.example
Server: 192.168.1.7
Address: 192.168.1.7#53

Name: golinuxhub-client.example
Address: 192.169.1.7

[root@golinuxhub-client named]# nslookup golinuxhub-server.example
Server: 192.168.1.7
Address: 192.168.1.7#53

Name: golinuxhub-server.example
Address: 192.168.1.5

I hope the article was useful.