DNS Server Installation Step by Step Using CentOS 6.5
DNS,
Domain
Name
System, translates hostnames or URLs into IP addresses. For example if we type www.unixmen.com in browser, the DNS server translates the domain name into its associated ip address. Since the IP addresses are hard to remember, DNS servers are used to translate the hostnames like
www.unixmen.com to
173.xxx.xx.xxx. So it makes easy to remember the domain names instead of its IP address.
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 MX 10 mail.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
mail IN A 192.168.1.50
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
mail IN A 192.168.1.50
100 IN PTR masterdns.unixmen.local.
101 IN PTR secondarydns.unixmen.local.
102 IN PTR client.unixmen.local.
50 IN PTR mail.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.