Monday, April 13, 2015

[Ubuntu]: How To Setup DNS Server In Ubuntu 14.10, CentOS 6.0 & CentOS 7.0

How To Setup DNS Server In Ubuntu

Scenario

For the purpose of this tutorial, I will be using three nodes. One will be acting as Master DNS server, the second system will be acting as Secondary DNS, and the third will be our DNS client. Here are my three systems details.

Primary (Master) DNS Server Details:

Operating System     : Ubuntu 14.04 64bit minimal server
Hostname             : masterdns.unixmen.local
IP Address           : 192.168.1.101/24

Secondary (Slave) DNS Server Details:

Operating System     : Ubuntu 14.04 32bit minimal server
Hostname             : secondarydns.unixmen.local
IP Address           : 192.168.1.102/24

Client Details:

Operating System     : Ubuntu 14.04 desktop
Hostname             : client.unixmen.local
IP Address           : 192.168.1.103/24

Setup Caching Server

In this configuration BIND9 will find the answer to name queries and remember the answer for the next query. This can be useful for a slow internet connection. By caching DNS queries, you will reduce bandwidth and (more importantly) latency.
The default configuration is setup to act as a caching server. All that is required is simply adding the IP Addresses of your ISP’s DNS servers. Caching server is opt for low Internet connection.
Install bind9 packages using command:
sudo apt-get install bind9 bind9utils bind9-doc
Then edit /etc/bind/named.conf.options file,
sudo vi /etc/bind/named.conf.options
Simply uncomment and edit the following in /etc/bind/named.conf.options:
forwarders {
 8.8.8.8;
};
Restart bind9 service.
sudo service bind9 restart

Test Caching Server

Run the following command to test it.
dig -x 127.0.0.1
Sample output:
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 60612
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 3

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

;; ANSWER SECTION:
1.0.0.127.in-addr.arpa.    604800    IN    PTR    localhost.

;; AUTHORITY SECTION:
127.in-addr.arpa.    604800    IN    NS    localhost.

;; ADDITIONAL SECTION:
localhost.        604800    IN    A    127.0.0.1
localhost.        604800    IN    AAAA    ::1

;; Query time: 4 msec
;; SERVER: 192.168.1.101#53(192.168.1.101)
;; WHEN: Thu Apr 09 14:51:36 IST 2015
;; MSG SIZE  rcvd: 132

Setup Primary (Master) DNS Server

You can use the same server for both Primary and Caching server.
Install bind9 packages on your server if not installed.
sudo apt-get install bind9 bind9utils bind9-doc

1. Configure Master DNS Server

DNS configuration files are stored in /etc/bind directory. Primary configuration file is/etc/bind/namd.conf.
Edit ‘/etc/bind/named.conf’ file.
sudo vi /etc/bind/named.conf
Make sure it contains the following lines. If not, add them.
include "/etc/bind/named.conf.options";
include "/etc/bind/named.conf.local";
include "/etc/bind/named.conf.default-zones";
Save and close the file.
Then, edit named.conf.local,
sudo vi /etc/bind/named.conf.local
Add the lines as shown in bold:
zone "unixmen.local" {
        type master;
        file "/etc/bind/forward.unixmen";
        allow-transfer { 192.168.1.102; };
        also-notify { 192.168.1.102; };
 };

zone "1.168.192.in-addr.arpa" {
        type master;
        file "/etc/bind/reverse.unixmen";
        allow-transfer { 192.168.1.102; };
        also-notify { 192.168.1.102; };
 };
Here,
  • forward.unixmen – Forward zone file
  • reverse.unixmen – Reverse zone file
  • 192.168.1.102 – Slave DNS server

2. Create Zone files

Create forward and reverse zone files which we defiend in the‘/etc/bind/named.conf.local’ file.

2.1 Create Forward Zone

Create Forward Zone file name forward.unixmen in /etc/bind/zones,
sudo vi /etc/bind/forward.unixmen
Add the following lines:
$TTL 86400
@   IN  SOA     masterdns.unixmen.local. root.unixmen.local. (
        2011071001  ;Serial
        3600        ;Refresh
        1800        ;Retry
        604800      ;Expire
        86400       ;Minimum TTL
)
@       IN  NS          masterdns.unixmen.local.
@       IN  NS          secondarydns.unixmen.local.
@       IN  A           192.168.1.101
@       IN  A           192.168.1.102
@       IN  A           192.168.1.103
masterdns       IN  A   192.168.1.101
secondarydns    IN  A   192.168.1.102
client          IN  A   192.168.1.103

2.2 Create Reverse Zone

Create Forward Zone file name reverse.unixmen in /etc/bind/zones,
sudo vi /etc/bind/reverse.unixmen
Add the following lines:
$TTL 86400
@   IN  SOA     masterdns.unixmen.local. root.unixmen.local. (
        2011071002  ;Serial
        3600        ;Refresh
        1800        ;Retry
        604800      ;Expire
        86400       ;Minimum TTL
)
@       IN  NS          masterdns.unixmen.local.
@       IN  NS          secondarydns.unixmen.local.
@       IN  PTR         unixmen.local.
masterdns       IN  A   192.168.1.101
secondarydns    IN  A   192.168.1.102
client          IN  A   192.168.1.103
101     IN  PTR         masterdns.unixmen.local.
102     IN  PTR         secondarydns.unixmen.local.
103     IN  PTR         client.unixmen.local.

3. Configuring Permissions, Ownership for Bind

Run the following commands one by one:
sudo chmod -R 755 /etc/bind
sudo chown -R bind:bind /etc/bind

4. Test DNS configuration and zone files for any syntax errors

Check DNS default configuration file:
sudo named-checkconf /etc/bind/named.conf
sudo named-checkconf /etc/bind/named.conf.local
If it returns nothing, your configuration is valid.
Check Forward zone:
sudo named-checkzone unixmen.local /etc/bind/forward.unixmen
Sample output:
zone unixmen.local/IN: loaded serial 2011071001
OK
Check reverse zone:
sudo named-checkzone unixmen.local /etc/bind/reverse.unixmen
Sample Output:
zone unixmen.local/IN: loaded serial 2011071002
OK
Restart bind9 service.
sudo service bind9 restart
Add the DNS Server details in your network interface config file.
sudo vi /etc/network/interfaces
Add the nameserver IP address:
auto eth0
iface eth0 inet static
        address 192.168.1.101
        netmask 255.255.255.0
        network 192.168.1.0
        broadcast 192.168.1.255
        gateway 192.168.1.1
        dns-nameservers 192.168.1.101
        dns-search unixmen.local
Reboot your system.

5. Test DNS Server

Method 1:
dig masterdns.unixmen.local
Sample Output:
; <<>> DiG 9.9.5-3ubuntu0.2-Ubuntu <<>> masterdns.unixmen.local
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 27712
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;masterdns.unixmen.local.    IN    A

;; ANSWER SECTION:
masterdns.unixmen.local. 86400    IN    A    192.168.1.101

;; AUTHORITY SECTION:
unixmen.local.        86400    IN    NS    masterdns.unixmen.local.
unixmen.local.        86400    IN    NS    secondarydns.unixmen.local.

;; ADDITIONAL SECTION:
secondarydns.unixmen.local. 86400 IN    A    192.168.1.102

;; Query time: 4 msec
;; SERVER: 192.168.1.101#53(192.168.1.101)
;; WHEN: Thu Apr 09 14:20:00 IST 2015
;; MSG SIZE  rcvd: 125
Method 2:
nslookup unixmen.local
Sample Output:
Server:        192.168.1.101
Address:    192.168.1.101#53

Name:    unixmen.local
Address: 192.168.1.101
Name:    unixmen.local
Address: 192.168.1.102
Name:    unixmen.local
Address: 192.168.1.103
Now the Primary DNS server is ready to use.
It is time to configure our Secondary DNS server.

Setup Secondary(Slave) DNS Server

Secondary DNS server is optional, but recommended. If the master DNS server goes down, the Secondary DNS server will take charge and answer the queries. You need an additional server to setup Slave DNS server.
Install bind9 packages using the following command:
sudo apt-get install bind9 bind9utils bind9-doc

1. Configure Slave DNS Server

Edit ‘/etc/bind/named.conf’ file.
sudo vi /etc/bind/named.conf
Make sure it contains the following lines. If not, add them.
include "/etc/bind/named.conf.options";
include "/etc/bind/named.conf.local";
include "/etc/bind/named.conf.default-zones";
Save and close the file.
Then, edit named.conf.local,
sudo vi /etc/bind/named.conf.local
Add the lines as shown in bold:
zone "unixmen.local" {
        type slave;
        file "/var/cache/bind/forward.unixmen";
        masters { 192.168.5.101; };
 };

zone "1.168.192.in-addr.arpa" {
        type slave;
        file "/var/cache/bind/reverse.unixmen";
        masters { 192.168.5.101; };
 };
Here,
  • forward.unixmen – Forward zone file
  • reverse.unixmen – Reverse zone file
  • 192.168.1.101 – Master DNS server
The zone file must be in /var/cache/bind/ because, by default, AppArmor only allows write access inside it.

3. Configuring Permissions, Ownership for Bind

Run the following commands one by one:
sudo chmod -R 755 /etc/bind
sudo chown -R bind:bind /etc/bind
Restart bind9 service.
sudo service bind9 restart

4. Add the DNS Server details

Add the DNS Server details in your network interface config file.
sudo vi /etc/network/interfaces
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet static
address 192.168.1.102
netmask 255.255.255.0
network 192.168.1.0
broadcast 192.168.1.255
gateway 192.168.1.1
dns-nameservers 192.168.1.101
dns-nameservers 192.168.1.102
dns-search home
Save and close the file.
Reboot your system.

5. Test DNS Server

After logging in to your server, run the following commands to check if DNS server is really working or not.
Method 1:
dig masterdns.unixmen.local
Sample Output:
; <<>> DiG 9.9.5-3-Ubuntu <<>> masterdns.unixmen.local
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 20290
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;masterdns.unixmen.local.    IN    A

;; ANSWER SECTION:
masterdns.unixmen.local. 86400    IN    A    192.168.1.101

;; AUTHORITY SECTION:
unixmen.local.        86400    IN    NS    masterdns.unixmen.local.
unixmen.local.        86400    IN    NS    secondarydns.unixmen.local.

;; ADDITIONAL SECTION:
secondarydns.unixmen.local. 86400 IN    A    192.168.1.102

;; Query time: 5 msec
;; SERVER: 192.168.1.101#53(192.168.1.101)
;; WHEN: Thu Apr 09 14:32:38 IST 2015
;; MSG SIZE  rcvd: 125
Method 2:
dig secondarydns.unixmen.local
Sample Output:
; <<>> DiG 9.9.5-3-Ubuntu <<>> secondarydns.unixmen.local
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 53461
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;secondarydns.unixmen.local. IN A

;; ANSWER SECTION:
secondarydns.unixmen.local. 86400 IN A 192.168.1.102

;; AUTHORITY SECTION:
unixmen.local. 86400 IN NS masterdns.unixmen.local.
unixmen.local. 86400 IN NS secondarydns.unixmen.local.

;; ADDITIONAL SECTION:
masterdns.unixmen.local. 86400 IN A 192.168.1.101

;; Query time: 5 msec
;; SERVER: 192.168.1.101#53(192.168.1.101)
;; WHEN: Thu Apr 09 14:33:02 IST 2015
;; MSG SIZE rcvd: 125
Method 3:
nslookup unixmen.local
Sample Output:
Server:        192.168.1.101
Address:    192.168.1.101#53

Name:    unixmen.local
Address: 192.168.1.101
Name:    unixmen.local
Address: 192.168.1.103
Name:    unixmen.local
Address: 192.168.1.102
Note: A zone is only transferred if the Serial Number on the Primary DNS server is larger than the one on the Secondary DNS server.

Client Side Configuration

Add the DNS server details in ‘/etc/resolv.conf’ file in all client systems
vi /etc/resolv.conf
# Generated by NetworkManager
search unixmen.local
nameserver 192.168.1.101
nameserver 192.168.1.102
Restart network service or reboot the system.

Test DNS Server

Now, you can test the DNS server using any one of the following commands:
dig masterdns.unixmen.local
dig secondarydns.unixmen.local

dig client.unixmen.local

nslookup unixmen.local
That’s all about now. The primary and secondary DNS servers are ready to use.
#####################################################
===================================================

DNS Server Installation Step by

 Step Using CentOS 6.5/6.4/6.3

Scenario


Primary(Master) DNS Server Details:

Operating System     : CentOS 6.5 server
Hostname             : masterdns.unixmen.local
IP Address           : 192.168.1.100/24

Secondary(Slave) DNS Server Details:

Operating System     : CentOS 6.5 server
Hostname             : secondarydns.unixmen.local
IP Address           : 192.168.1.101/24

Client Details:

Operating System     : CentOS 6.5 Desktop  
Hostname             : Client.unixmen.local
IP Address           : 192.168.1.102/24

Setup Primary(Master) DNS Server

[root@masterdns ~]# yum install bind* -y

1. Configure DNS Server

Add the lines as shown below in ‘/etc/named.conf’ file
[root@masterdns ~]# vi /etc/named.conf 
//
// named.conf
//
// Provided by Red Hat bind package to configure the ISC BIND named(8) DNS
// server as a caching only nameserver (as a localhost DNS resolver only).
//
// See /usr/share/doc/bind*/sample/ for example named configuration files.
//
options {
listen-on port 53 { 127.0.0.1; 192.168.1.100; }; ### Master DNS IP ###
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; 192.168.1.0/24; }; ### IP Range ### 
allow-transfer{ localhost; 192.168.1.101; };   ### Slave DNS IP ###
recursion yes;
dnssec-enable yes;
dnssec-validation yes;
dnssec-lookaside auto;
/* Path to ISC DLV key */
bindkeys-file "/etc/named.iscdlv.key";
managed-keys-directory "/var/named/dynamic";
};
logging {
        channel default_debug {
                file "data/named.run";
                severity dynamic;
        };
};
zone "." IN {
type hint;
file "named.ca";
};
zone"unixmen.local" IN {
type master;
file "forward.unixmen";
allow-update { none; };
};
zone"1.168.192.in-addr.arpa" IN {
type master;
file "reverse.unixmen";
allow-update { none; };
};
include "/etc/named.rfc1912.zones";
include "/etc/named.root.key";

2. Create Zone files

Create forward and reverse zone files which we mentioned in the ‘/etc/named.conf’ file.

2.1 Create Forward Zone

Create forward.unixmen file in the ‘/var/named’ directory.
[root@masterdns ~]# vi /var/named/forward.unixmen
$TTL 86400
@   IN  SOA     masterdns.unixmen.local. root.unixmen.local. (
        2011071001  ;Serial
        3600        ;Refresh
        1800        ;Retry
        604800      ;Expire
        86400       ;Minimum TTL
)
@       IN  NS          masterdns.unixmen.local.
@       IN  NS          secondarydns.unixmen.local.
@       IN  A           192.168.1.100
@       IN  A           192.168.1.101
@       IN  A           192.168.1.102
masterdns       IN  A   192.168.1.100
secondarydns    IN  A   192.168.1.101
client          IN  A   192.168.1.102

2.2 Create Reverse Zone

Create reverse.unixmen file in the ‘/var/named’ directory.
[root@masterdns ~]# vi /var/named/reverse.unixmen 
$TTL 86400
@   IN  SOA     masterdns.unixmen.local. root.unixmen.local. (
        2011071001  ;Serial
        3600        ;Refresh
        1800        ;Retry
        604800      ;Expire
        86400       ;Minimum TTL
)
@       IN  NS          masterdns.unixmen.local.
@       IN  NS          secondarydns.unixmen.local.
@       IN  PTR         unixmen.local.
masterdns       IN  A   192.168.1.100
secondarydns    IN  A   192.168.1.101
client          IN  A   192.168.1.102
100     IN  PTR         masterdns.unixmen.local.
101     IN  PTR         secondarydns.unixmen.local.
102     IN  PTR         client.unixmen.local.

3. Start the DNS service

[root@masterdns ~]# service named start
Starting named:                                            [  OK  ]
[root@masterdns ~]# chkconfig named on

4. Adjust iptables to allow DNS server from outside of the network

Add the lines as shown below in ‘/etc/sysconfig/iptables’ file.
[root@masterdns ~]# vi /etc/sysconfig/iptables
# Firewall configuration written by system-config-firewall
# Manual customization of this file is not recommended.
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -p udp -m state --state NEW --dport 53 -j ACCEPT
-A INPUT -p tcp -m state --state NEW --dport 53 -j ACCEPT
-A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
-A INPUT -p icmp -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT
-A INPUT -j REJECT --reject-with icmp-host-prohibited
-A FORWARD -j REJECT --reject-with icmp-host-prohibited
COMMIT

5. Restart iptables

[root@masterdns ~]# service iptables restart
iptables: Flushing firewall rules:                         [  OK  ]
iptables: Setting chains to policy ACCEPT: filter          [  OK  ]
iptables: Unloading modules:                               [  OK  ]
iptables: Applying firewall rules:                         [  OK  ]

6. Test DNS configuration and zone files for any syntax errors

[root@masterdns ~]# named-checkconf /etc/named.conf 
[root@masterdns ~]# named-checkzone unixmen.local /var/named/forward.unixmen 
zone unixmen.local/IN: loaded serial 2011071001
OK
[root@masterdns ~]# named-checkzone unixmen.local /var/named/reverse.unixmen 
zone unixmen.local/IN: loaded serial 2011071001
OK

7. Test DNS Server

[root@masterdns ~]# dig masterdns.unixmen.local
; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6_3.6 <<>> masterdns.unixmen.local
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 49834
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 1
;; QUESTION SECTION:
;masterdns.unixmen.local.INA
;; ANSWER SECTION:
masterdns.unixmen.local. 86400INA192.168.1.100
;; AUTHORITY SECTION:
unixmen.local.86400INNSsecondarydns.unixmen.local.
unixmen.local.86400INNSmasterdns.unixmen.local.
;; ADDITIONAL SECTION:
secondarydns.unixmen.local. 86400 INA192.168.1.101
;; Query time: 6 msec
;; SERVER: 192.168.1.100#53(192.168.1.100)
;; WHEN: Thu Mar  7 13:07:56 2013
;; MSG SIZE  rcvd: 114
[root@masterdns ~]# nslookup unixmen.local
Server:192.168.1.100
Address:192.168.1.100#53
Name:unixmen.local
Address: 192.168.1.102
Name:unixmen.local
Address: 192.168.1.100
Name:unixmen.local
Address: 192.168.1.101
Now the Primary DNS server is ready to use.

Setup Secondary(Slave) DNS Server

[root@secondarydns ~]# yum install bind* -y

1. Configure Slave DNS Server

Open the main configuration file ‘/etc/named.conf’ and add the lines as shown below.
[root@secondarydns ~]# vi /etc/named.conf 
//
// named.conf
//
// Provided by Red Hat bind package to configure the ISC BIND named(8) DNS
// server as a caching only nameserver (as a localhost DNS resolver only).
//
// See /usr/share/doc/bind*/sample/ for example named configuration files.
//
options {
listen-on port 53 { 127.0.0.1; 192.168.1.101; };
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; 192.168.1.0/24; };
recursion yes;
dnssec-enable yes;
dnssec-validation yes;
dnssec-lookaside auto;
/* Path to ISC DLV key */
bindkeys-file "/etc/named.iscdlv.key";
managed-keys-directory "/var/named/dynamic";
};
logging {
        channel default_debug {
                file "data/named.run";
                severity dynamic;
        };
};
zone "." IN {
type hint;
file "named.ca";
};
zone"unixmen.local" IN {
type slave;
file "slaves/unixmen.fwd";
masters { 192.168.1.100; };
};
zone"1.168.192.in-addr.arpa" IN {
type slave;
file "slaves/unixmen.rev";
masters { 192.168.1.100; };
};
include "/etc/named.rfc1912.zones";
include "/etc/named.root.key";

2. Start the DNS Service

[root@secondarydns ~]# service named start
Generating /etc/rndc.key:                                  [  OK  ]
Starting named:                                            [  OK  ]
[root@secondarydns ~]# chkconfig named on
Now the forward and reverse zones are automatically replicated from Master DNS server to‘/var/named/slaves/’ in Secondary DNS server.
[root@secondarydns ~]# ls /var/named/slaves/
unixmen.fwd  unixmen.rev
[root@secondarydns ~]# cat /var/named/slaves/unixmen.fwd 
$ORIGIN .
$TTL 86400; 1 day
unixmen.localIN SOAmasterdns.unixmen.local. root.unixmen.local. (
2011071001 ; serial
3600       ; refresh (1 hour)
1800       ; retry (30 minutes)
604800     ; expire (1 week)
86400      ; minimum (1 day)
)
NS masterdns.unixmen.local.
NS secondarydns.unixmen.local.
A192.168.1.100
A192.168.1.101
A192.168.1.102
$ORIGIN unixmen.local.
clientA192.168.1.102
masterdnsA192.168.1.100
secondarydnsA192.168.1.101
[root@secondarydns ~]# cat /var/named/slaves/unixmen.rev 
$ORIGIN .
$TTL 86400; 1 day
1.168.192.in-addr.arpaIN SOAmasterdns.unixmen.local. root.unixmen.local. (
2011071001 ; serial
3600       ; refresh (1 hour)
1800       ; retry (30 minutes)
604800     ; expire (1 week)
86400      ; minimum (1 day)
)
NS masterdns.unixmen.local.
NS secondarydns.unixmen.local.
PTRunixmen.local.
$ORIGIN 1.168.192.in-addr.arpa.
100PTRmasterdns.unixmen.local.
101PTRsecondarydns.unixmen.local.
102PTRclient.unixmen.local.
clientA192.168.1.102
masterdnsA192.168.1.100
secondarydnsA192.168.1.101

3. Add the DNS Server details to all systems

[root@secondarydns ~]# vi /etc/resolv.conf
# Generated by NetworkManager
search ostechnix.com
nameserver 192.168.1.100
nameserver 192.168.1.101
nameserver 8.8.8.8

4. Test DNS Server

[root@secondarydns ~]# dig masterdns.unixmen.local
; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6_3.6 <<>> masterdns.unixmen.local
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 21487
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 1
;; QUESTION SECTION:
;masterdns.unixmen.local.INA
;; ANSWER SECTION:
masterdns.unixmen.local. 86400INA192.168.1.100
;; AUTHORITY SECTION:
unixmen.local.86400INNSmasterdns.unixmen.local.
unixmen.local.86400INNSsecondarydns.unixmen.local.
;; ADDITIONAL SECTION:
secondarydns.unixmen.local. 86400 INA192.168.1.101
;; Query time: 15 msec
;; SERVER: 192.168.1.100#53(192.168.1.100)
;; WHEN: Thu Mar  7 13:27:57 2013
;; MSG SIZE  rcvd: 114
[root@secondarydns ~]# dig secondarydns.unixmen.local
; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6_3.6 <<>> secondarydns.unixmen.local
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 20958
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 1
;; QUESTION SECTION:
;secondarydns.unixmen.local.INA
;; ANSWER SECTION:
secondarydns.unixmen.local. 86400 INA192.168.1.101
;; AUTHORITY SECTION:
unixmen.local.86400INNSmasterdns.unixmen.local.
unixmen.local.86400INNSsecondarydns.unixmen.local.
;; ADDITIONAL SECTION:
masterdns.unixmen.local. 86400INA192.168.1.100
;; Query time: 4 msec
;; SERVER: 192.168.1.100#53(192.168.1.100)
;; WHEN: Thu Mar  7 13:31:53 2013
;; MSG SIZE  rcvd: 114
[root@secondarydns ~]# nslookup unixmen.local
Server:192.168.1.100
Address:192.168.1.100#53
Name:unixmen.local
Address: 192.168.1.101
Name:unixmen.local
Address: 192.168.1.102
Name:unixmen.local
Address: 192.168.1.100
Client Side Configuration
Add the DNS server details in ‘/etc/resolv.conf’ file in all client systems
[root@client unixmen]# vi /etc/resolv.conf
# Generated by NetworkManager
search unixmen.local
nameserver 192.168.1.100
nameserver 192.168.1.101
nameserver 8.8.8.8

Test DNS Server

[root@client unixmen]# dig masterdns.unixmen.local
; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6 <<>> masterdns.unixmen.local
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 19496
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 1
;; QUESTION SECTION:
;masterdns.unixmen.local.INA
;; ANSWER SECTION:
masterdns.unixmen.local. 86400INA192.168.1.100
;; AUTHORITY SECTION:
unixmen.local.86400INNSmasterdns.unixmen.local.
unixmen.local.86400INNSsecondarydns.unixmen.local.
;; ADDITIONAL SECTION:
secondarydns.unixmen.local. 86400 INA192.168.1.101
;; Query time: 30 msec
;; SERVER: 192.168.1.100#53(192.168.1.100)
;; WHEN: Thu Mar  7 13:47:55 2013
;; MSG SIZE  rcvd: 114
[root@client unixmen]# dig secondarydns.unixmen.local
; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6 <<>> secondarydns.unixmen.local
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 14852
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 1
;; QUESTION SECTION:
;secondarydns.unixmen.local.INA
;; ANSWER SECTION:
secondarydns.unixmen.local. 86400 INA192.168.1.101
;; AUTHORITY SECTION:
unixmen.local.86400INNSsecondarydns.unixmen.local.
unixmen.local.86400INNSmasterdns.unixmen.local.
;; ADDITIONAL SECTION:
masterdns.unixmen.local. 86400INA192.168.1.100
;; Query time: 8 msec
;; SERVER: 192.168.1.100#53(192.168.1.100)
;; WHEN: Thu Mar  7 13:48:38 2013
;; MSG SIZE  rcvd: 114
[root@client unixmen]# dig client.unixmen.local
; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6 <<>> client.unixmen.local
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 14604
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2
;; QUESTION SECTION:
;client.unixmen.local.INA
;; ANSWER SECTION:
client.unixmen.local.86400INA192.168.1.102
;; AUTHORITY SECTION:
unixmen.local.86400INNSmasterdns.unixmen.local.
unixmen.local.86400INNSsecondarydns.unixmen.local.
;; ADDITIONAL SECTION:
masterdns.unixmen.local. 86400INA192.168.1.100
secondarydns.unixmen.local. 86400 INA192.168.1.101
;; Query time: 5 msec
;; SERVER: 192.168.1.100#53(192.168.1.100)
;; WHEN: Thu Mar  7 13:49:11 2013
;; MSG SIZE  rcvd: 137
[root@client unixmen]# nslookup unixmen.local
Server:192.168.1.100
Address:192.168.1.100#53
Name:unixmen.local
Address: 192.168.1.102
Name:unixmen.local
Address: 192.168.1.100
Name:unixmen.local
Address: 192.168.1.101
Now the primary and secondary DNS servers are ready.
#######################################################==========================================================

Setting Up DNS Server On CentOS 7

DNS Server Installation

Scenario

For the purpose of this tutorial, I will be using three nodes. One will be acting as Master DNS server, the second system will be acting as Secondary DNS, and the third will be our DNS client. Here are my three systems details.

Primary (Master) DNS Server Details:

Operating System     : CentOS 7 minimal server
Hostname             : masterdns.unixmen.local
IP Address           : 192.168.1.101/24

Secondary (Slave) DNS Server Details:

Operating System     : CentOS 7 minimal server
Hostname             : secondarydns.unixmen.local
IP Address           : 192.168.1.102/24

Client Details:

Operating System     : CentOS 6.5 Desktop  
Hostname             : client.unixmen.local
IP Address           : 192.168.1.103/24

Setup Primary (Master) DNS Server

Install bind9 packages on your server.
yum install bind bind-utils -y

1. Configure DNS Server

Edit ‘/etc/named.conf’ file.
vi /etc/named.conf
Add the lines as shown in bold:
//
// named.conf
//
// Provided by Red Hat bind package to configure the ISC BIND named(8) DNS
// server as a caching only nameserver (as a localhost DNS resolver only).
//
// See /usr/share/doc/bind*/sample/ for example named configuration files.
//

options {
    listen-on port 53 { 127.0.0.1; 192.168.1.101;}; ### Master DNS IP ###
#    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; 192.168.1.0/24;}; ### IP Range ###
    allow-transfer{ localhost; 192.168.1.102; };   ### Slave DNS IP ###

    /* 
     - If you are building an AUTHORITATIVE DNS server, do NOT enable recursion.
     - If you are building a RECURSIVE (caching) DNS server, you need to enable 
       recursion. 
     - If your recursive DNS server has a public IP address, you MUST enable access 
       control to limit queries to your legitimate users. Failing to do so will
       cause your server to become part of large scale DNS amplification 
       attacks. Implementing BCP38 within your network would greatly
       reduce such attack surface 
    */
    recursion yes;

    dnssec-enable yes;
    dnssec-validation yes;
    dnssec-lookaside auto;

    /* Path to ISC DLV key */
    bindkeys-file "/etc/named.iscdlv.key";

    managed-keys-directory "/var/named/dynamic";

    pid-file "/run/named/named.pid";
    session-keyfile "/run/named/session.key";
};

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

zone "." IN {
    type hint;
    file "named.ca";
};

zone "unixmen.local" IN {
type master;
file "forward.unixmen";
allow-update { none; };
};
zone "1.168.192.in-addr.arpa" IN {
type master;
file "reverse.unixmen";
allow-update { none; };
};

include "/etc/named.rfc1912.zones";
include "/etc/named.root.key";

2. Create Zone files

Create forward and reverse zone files which we mentioned in the ‘/etc/named.conf’ file.

2.1 Create Forward Zone

Create forward.unixmen file in the ‘/var/named’ directory.
vi /var/named/forward.unixmen
Add the following lines:
$TTL 86400
@   IN  SOA     masterdns.unixmen.local. root.unixmen.local. (
        2011071001  ;Serial
        3600        ;Refresh
        1800        ;Retry
        604800      ;Expire
        86400       ;Minimum TTL
)
@       IN  NS          masterdns.unixmen.local.
@       IN  NS          secondarydns.unixmen.local.
@       IN  A           192.168.1.101
@       IN  A           192.168.1.102
@       IN  A           192.168.1.103
masterdns       IN  A   192.168.1.101
secondarydns    IN  A   192.168.1.102
client          IN  A   192.168.1.103

2.2 Create Reverse Zone

Create reverse.unixmen file in the ‘/var/named’ directory.
vi /var/named/reverse.unixmen
Add the following lines:
$TTL 86400
@   IN  SOA     masterdns.unixmen.local. root.unixmen.local. (
        2011071001  ;Serial
        3600        ;Refresh
        1800        ;Retry
        604800      ;Expire
        86400       ;Minimum TTL
)
@       IN  NS          masterdns.unixmen.local.
@       IN  NS          secondarydns.unixmen.local.
@       IN  PTR         unixmen.local.
masterdns       IN  A   192.168.1.101
secondarydns    IN  A   192.168.1.102
client          IN  A   192.168.1.103
101     IN  PTR         masterdns.unixmen.local.
102     IN  PTR         secondarydns.unixmen.local.
103     IN  PTR         client.unixmen.local.

3. Start the DNS service

Enable and start DNS service:
systemctl enable named
systemctl start named

4. Firewall Configuration

We must allow the DNS service default port 53 through firewall.
firewall-cmd --permanent --add-port=53/tcp

5. Restart Firewall

firewall-cmd --reload

6. Configuring Permissions, Ownership, and SELinux

Run the following commands one by one:
chgrp named -R /var/named
chown -v root:named /etc/named.conf
restorecon -rv /var/named
restorecon /etc/named.conf

7. Test DNS configuration and zone files for any syntax errors

Check DNS default configuration file:
named-checkconf /etc/named.conf
If it returns nothing, your configuration file is valid.
Check Forward zone:
named-checkzone unixmen.local /var/named/forward.unixmen
Sample output:
zone unixmen.local/IN: loaded serial 2011071001
OK
Check reverse zone:
named-checkzone unixmen.local /var/named/reverse.unixmen 
Sample Output:
zone unixmen.local/IN: loaded serial 2011071001
OK
Add the DNS Server details in your network interface config file.
vi /etc/sysconfig/network-scripts/ifcfg-enp0s3
TYPE="Ethernet"
BOOTPROTO="none"
DEFROUTE="yes"
IPV4_FAILURE_FATAL="no"
IPV6INIT="yes"
IPV6_AUTOCONF="yes"
IPV6_DEFROUTE="yes"
IPV6_FAILURE_FATAL="no"
NAME="enp0s3"
UUID="5d0428b3-6af2-4f6b-9fe3-4250cd839efa"
ONBOOT="yes"
HWADDR="08:00:27:19:68:73"
IPADDR0="192.168.1.101"
PREFIX0="24"
GATEWAY0="192.168.1.1"
DNS="192.168.1.101"
IPV6_PEERDNS="yes"
IPV6_PEERROUTES="yes"
Edit file /etc/resolv.conf,
vi /etc/resolv.conf
Add the name server ip address:
nameserver      192.168.1.101
Save and close the file.
Restart network service:
systemctl restart network

8. Test DNS Server

dig masterdns.unixmen.local
Sample Output:
; <<>> DiG 9.9.4-RedHat-9.9.4-14.el7 <<>> masterdns.unixmen.local
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 25179
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;masterdns.unixmen.local.    IN    A

;; ANSWER SECTION:
masterdns.unixmen.local. 86400    IN    A    192.168.1.101

;; AUTHORITY SECTION:
unixmen.local.        86400    IN    NS    secondarydns.unixmen.local.
unixmen.local.        86400    IN    NS    masterdns.unixmen.local.

;; ADDITIONAL SECTION:
secondarydns.unixmen.local. 86400 IN    A    192.168.1.102

;; Query time: 0 msec
;; SERVER: 192.168.1.101#53(192.168.1.101)
;; WHEN: Wed Aug 20 16:20:46 IST 2014
;; MSG SIZE  rcvd: 125
nslookup unixmen.local
Sample Output:
Server:        192.168.1.101
Address:    192.168.1.101#53

Name:    unixmen.local
Address: 192.168.1.103
Name:    unixmen.local
Address: 192.168.1.101
Name:    unixmen.local
Address: 192.168.1.102
Now the Primary DNS server is ready to use.
It is time to configure our Secondary DNS server.

Setup Secondary(Slave) DNS Server

Install bind packages using the following command:
yum install bind bind-utils -y

1. Configure Slave DNS Server

Edit file ‘/etc/named.conf’:
vi /etc/named.conf
Make the changes as shown in bold.
//
// named.conf
//
// Provided by Red Hat bind package to configure the ISC BIND named(8) DNS
// server as a caching only nameserver (as a localhost DNS resolver only).
//
// See /usr/share/doc/bind*/sample/ for example named configuration files.
//
options {
listen-on port 53 { 127.0.0.1; 192.168.1.102; };
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; 192.168.1.0/24; };
.
.
.
.
zone "." IN {
type hint;
file "named.ca";
};
zone "unixmen.local" IN {
type slave;
file "slaves/unixmen.fwd";
masters { 192.168.1.101; };
};
zone "1.168.192.in-addr.arpa" IN {
type slave;
file "slaves/unixmen.rev";
masters { 192.168.1.101; };
};
include "/etc/named.rfc1912.zones";
include "/etc/named.root.key";

2. Start the DNS Service

systemctl enable named
systemctl start named
Now the forward and reverse zones are automatically replicated from Master DNS server to ‘/var/named/slaves/’ in Secondary DNS server.
ls /var/named/slaves/
Sample Output:
unixmen.fwd  unixmen.rev

3. Add the DNS Server details

Add the DNS Server details in your network interface config file.
vi /etc/sysconfig/network-scripts/ifcfg-enp0s3
TYPE="Ethernet"
BOOTPROTO="none"
DEFROUTE="yes"
IPV4_FAILURE_FATAL="no"
IPV6INIT="yes"
IPV6_AUTOCONF="yes"
IPV6_DEFROUTE="yes"
IPV6_FAILURE_FATAL="no"
NAME="enp0s3"
UUID="5d0428b3-6af2-4f6b-9fe3-4250cd839efa"
ONBOOT="yes"
HWADDR="08:00:27:19:68:73"
IPADDR0="192.168.1.102"
PREFIX0="24"
GATEWAY0="192.168.1.1"
DNS1="192.168.1.101"
DNS2="192.168.1.102"
IPV6_PEERDNS="yes"
IPV6_PEERROUTES="yes"
Edit file /etc/resolv.conf,
vi /etc/resolv.conf
Add the name server ip address:
nameserver      192.168.1.101
nameserver      192.168.1.102
Save and close the file.
Restart network service:
systemctl restart network

4. Firewall Configuration

We must allow the DNS service default port 53 through firewall.
firewall-cmd --permanent --add-port=53/tcp

5. Restart Firewall

firewall-cmd --reload

6. Configuring Permissions, Ownership, and SELinux

chgrp named -R /var/named
chown -v root:named /etc/named.conf
restorecon -rv /var/named
restorecon /etc/named.conf

7. Test DNS Server

dig masterdns.unixmen.local
Sample Output:
; <<>> DiG 9.9.4-RedHat-9.9.4-14.el7 <<>> masterdns.unixmen.local
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 18204
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;masterdns.unixmen.local.    IN    A

;; ANSWER SECTION:
masterdns.unixmen.local. 86400    IN    A    192.168.1.101

;; AUTHORITY SECTION:
unixmen.local.        86400    IN    NS    masterdns.unixmen.local.
unixmen.local.        86400    IN    NS    secondarydns.unixmen.local.

;; ADDITIONAL SECTION:
secondarydns.unixmen.local. 86400 IN    A    192.168.1.102

;; Query time: 0 msec
;; SERVER: 192.168.1.102#53(192.168.1.102)
;; WHEN: Wed Aug 20 17:04:30 IST 2014
;; MSG SIZE  rcvd: 125
dig secondarydns.unixmen.local
Sample Output:
; <<>> DiG 9.9.4-RedHat-9.9.4-14.el7 <<>> secondarydns.unixmen.local
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 60819
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;secondarydns.unixmen.local.    IN    A

;; ANSWER SECTION:
secondarydns.unixmen.local. 86400 IN    A    192.168.1.102

;; AUTHORITY SECTION:
unixmen.local.        86400    IN    NS    masterdns.unixmen.local.
unixmen.local.        86400    IN    NS    secondarydns.unixmen.local.

;; ADDITIONAL SECTION:
masterdns.unixmen.local. 86400    IN    A    192.168.1.101

;; Query time: 0 msec
;; SERVER: 192.168.1.102#53(192.168.1.102)
;; WHEN: Wed Aug 20 17:05:50 IST 2014
;; MSG SIZE  rcvd: 125
nslookup unixmen.local
Sample Output:
Server:        192.168.1.102
Address:    192.168.1.102#53

Name:    unixmen.local
Address: 192.168.1.101
Name:    unixmen.local
Address: 192.168.1.103
Name:    unixmen.local
Address: 192.168.1.102

Client Side Configuration

Add the DNS server details in ‘/etc/resolv.conf’ file in all client systems
vi /etc/resolv.conf
# Generated by NetworkManager
search unixmen.local
nameserver 192.168.1.101
nameserver 192.168.1.102
Restart network service or reboot the system.

Test DNS Server

Now, you can test the DNS server using any one of the following commands:
dig masterdns.unixmen.local
dig secondarydns.unixmen.local

dig client.unixmen.local

nslookup unixmen.local
That’s all about now. The primary and secondary DNS servers are ready to use.

Command (IF DNS not working)
# bind chrootadmin -d
# bind chrootadmin -e

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