DNS Server Installation Step by Step Using CentOS 6.5DNS, 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 likewww.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.
