Setup DNS Server Step by Step in Centos - Rhel -Scientific Linux

SETUP DNS SERVER STEP BY STEP IN CENTOS - RHEL -

SCIENTIFIC LINUX

DNS SERVER INSTALLATION IN CENTOS 6.5 This how-to tutorial will show you how to install and configure Primary and Secondary DNS server. The

steps provided here were tested in CentOS 6.5 32 bit edition, but it should work in RHEL 6.x(x stands for

version) and Scientific Linux 6.x too.

Scenario

Here are my test setup scenario

[A] Primary(Master) DNS Server Details:

Operating System : CentOS 6.5 32 bit (Minimal Server)

Hostname : masterdns.ostechnix.com

IP Address : 192.168.1.200/24

[B] Secondary(Slave) DNS Server Details:

Operating System : CentOS 6.5 32 bit (Minimal Server)

Hostname : slavedns.ostechnix.com

IP Address : 192.168.1.201/24

SETUP PRIMARY(MASTER) DNS SERVER [root@masterdns ~]# yum install bind* -y

1. Configure DNS Server

The main configuration of the DNS will look like below. Edit and add the entries below which were marked

as bold in this configuration files. [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; 192.168.1.200;}; ## 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; 192.168.1.201; }; ## 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"ostechnix.com" IN {

type master;

file "fwd.ostechnix.com";

allow-update { none; };

};

zone"1.168.192.in-addr.arpa" IN {

type master;

file "rev.ostechnix.com";

allow-update { none; };

};

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

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

2. Create Zone files

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

[A] Create Forward Zone

Create ‘fwd.ostechnix.com’ file in the ‘/var/named’ directory and add the entries for forward zone as shown

below. [root@masterdns ~]# vi /var/named/fwd.ostechnix.com

$TTL 86400

@ IN SOA masterdns.ostechnix.com. root.ostechnix.com. (

2011071001 ;Serial

3600 ;Refresh

1800 ;Retry

604800 ;Expire

86400 ;Minimum TTL

)

@IN NS masterdns.ostechnix.com.

@IN NS slavedns.ostechnix.com.masterdns IN A 192.168.1.200

slavedns IN A 192.168.1.201

[B] Create Reverse Zone

Create ‘rev.ostechnix.com’ file in the ‘/var/named’ directory and add the entries for reverse zone as shown

below. [root@masterdns ~]# vi /var/named/rev.ostechnix.com

$TTL 86400

@ IN SOA masterdns.ostechnix.com. root.ostechnix.com. (

2011071001 ;Serial

3600 ;Refresh

1800 ;Retry

604800 ;Expire

86400 ;Minimum TTL

)

@IN NS masterdns.ostechnix.com.

@IN NS slavedns.ostechnix.com.

masterdnsIN A 192.168.1.200

slavedns IN A 192.168.1.201

200 IN PTR masterdns.ostechnix.com.

201 IN PTR slavedns.ostechnix.com.

3. Start the bind service

[root@masterdns ~]# service named start

Generating /etc/rndc.key: [ OK ]

Starting named: [ OK ]

[root@masterdns ~]# chkconfig named on

4. Allow DNS Server through iptables

Add the lines shown in bold letters in ‘/etc/sysconfig/iptables’ file. This will allow all clients to access the

DNS server. [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 to save the changes

[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 syntax errors of DNS configuration and zone files

[A] Check DNS Config file

[root@masterdns ~]# named-checkconf /etc/named.conf

[root@masterdns ~]# named-checkconf /etc/named.rfc1912.zones

[B] Check zone files

[root@masterdns ~]# named-checkzone ostechnix.com /var/named/fwd.ostechnix.com

zone ostechnix.com/IN: loaded serial 2011071001

OK

[root@masterdns ~]# named-checkzone ostechnix.com /var/named/rev.ostechnix.com

zone ostechnix.com/IN: loaded serial 2011071001

OK

[root@masterdns ~]#

7. Test DNS Server

Method A:

[root@masterdns ~]# dig masterdns.ostechnix.com

; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6_3.6 <<>> masterdns.ostechnix.com

;; global options: +cmd

;; Got answer:

;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 11496

;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 1

;; QUESTION SECTION:

;masterdns.ostechnix.com.INA

;; ANSWER SECTION:

masterdns.ostechnix.com. 86400INA192.168.1.200

;; AUTHORITY SECTION:

ostechnix.com.86400INNSmasterdns.ostechnix.com.

ostechnix.com.86400INNSslavedns.ostechnix.com.

;; ADDITIONAL SECTION:

slavedns.ostechnix.com.86400INA192.168.1.201

;; Query time: 5 msec

;; SERVER: 192.168.1.200#53(192.168.1.200)

;; WHEN: Sun Mar 3 12:48:35 2013

;; MSG SIZE rcvd: 110

Method B:

[root@masterdns ~]# dig -x 192.168.1.200

; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6_3.6 <<>> -x 192.168.1.200


;; Got answer:




;200.1.168.192.in-addr.arpa.INPTR

;; ANSWER SECTION:

200.1.168.192.in-addr.arpa. 86400 INPTRmasterdns.ostechnix.com.


1.168.192.in-addr.arpa.86400INNSmasterdns.ostechnix.com.

1.168.192.in-addr.arpa.86400INNSslavedns.ostechnix.com.





;; SERVER: 192.168.1.200#53(192.168.1.200)

;; WHEN: Sun Mar 3 12:49:53 2013


Method C:

[root@masterdns ~]# nslookup masterdns

Server:192.168.1.200

Address:192.168.1.200#53

Name:masterdns.ostechnix.com

Address: 192.168.1.200

Thats it. Now the Primary DNS server is ready

SETUP SECONDARY(SLAVE) DNS SERVER [root@slavedns ~]# yum install bind* -y

1. Configure Slave DNS Server

Open the main configuration file ‘/etc/named.conf’ and add the lines as shown in bold letters. [root@slavedns ~]# 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; 192.168.1.201; }; ## Slve 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 ##

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"ostechnix.com" IN {

type slave;

file "slaves/ostechnix.fwd";

masters { 192.168.1.200; };

};

zone"1.168.192.in-addr.arpa" IN {

type slave;

file "slaves/ostechnix.rev";

masters { 192.168.1.200; };

};

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

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

2. Start the DNS Service

[root@slavedns ~]# service named start

Generating /etc/rndc.key: [ OK ]

Starting named: [ OK ]

[root@slavedns ~]# chkconfig named on

Now the forward and reverse zones are automatically replicated from Master DNS server to Slave DNS

server.

To verify, goto DNS database location(i.e ‘/var/named/slaves’) and use command ‘ls’. [root@slavedns ~]# cd /var/named/slaves/

[root@slavedns slaves]# ls

ostechnix.fwd ostechnix.rev

The forward and reverse zones are automatically replicated from Master DNS. Now check the zone files

whether the correct zone files are replicated or not.

[A] Check Forward zone:

[root@slavedns slaves]# cat ostechnix.fwd

$ORIGIN .

$TTL 86400; 1 day

ostechnix.comIN SOAmasterdns.ostechnix.com. root.ostechnix.com. (

2011071001 ; serial

3600 ; refresh (1 hour)

1800 ; retry (30 minutes)

604800 ; expire (1 week)

86400 ; minimum (1 day)

)

NSmasterdns.ostechnix.com.

NSslavedns.ostechnix.com.

$ORIGIN ostechnix.com.

masterdnsA192.168.1.200

slavedns A192.168.1.201

[B] Check Reverse zone:

[root@slavedns slaves]# cat ostechnix.rev

$ORIGIN .

$TTL 86400; 1 day

1.168.192.in-addr.arpaIN SOAmasterdns.ostechnix.com. root.ostechnix.com. (

2011071001 ; serial

3600 ; refresh (1 hour)

1800 ; retry (30 minutes)

604800 ; expire (1 week)

86400 ; minimum (1 day)

)

NSmasterdns.ostechnix.com.

NSslavedns.ostechnix.com.

$ORIGIN 1.168.192.in-addr.arpa.

200PTRmasterdns.ostechnix.com.

201PTRslavedns.ostechnix.com.

masterdnsA192.168.1.200

slavedns A192.168.1.201

3. Add the DNS Server details to all systems

[root@slavedns ~]# vi /etc/resolv.conf

# Generated by NetworkManager

search ostechnix.com

nameserver 192.168.1.200

nameserver 192.168.1.201

nameserver 8.8.8.8

4. Test DNS Server

Method A:

[root@slavedns ~]# dig slavedns.ostechnix.com

; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6_3.6 <<>> slavedns.ostechnix.com


;; Got answer:




;slavedns.ostechnix.com.INA

;; ANSWER SECTION:








;; SERVER: 192.168.1.200#53(192.168.1.200)

;; WHEN: Sun Mar 3 13:00:17 2013


Method B:

[root@slavedns ~]# dig masterdns.ostechnix.com

; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6_3.6 <<>> masterdns.ostechnix.com


;; Got answer:




;masterdns.ostechnix.com.INA

;; ANSWER SECTION:








;; SERVER: 192.168.1.200#53(192.168.1.200)

;; WHEN: Sun Mar 3 13:01:02 2013


Method C:

[root@slavedns ~]# nslookup slavedns

Server:192.168.1.200

Address:192.168.1.200#53

Name:slavedns.ostechnix.com

Address: 192.168.1.201

Method D:

[root@slavedns ~]# nslookup masterdns

Server:192.168.1.200

Address:192.168.1.200#53

Name:masterdns.ostechnix.com

Address: 192.168.1.200

Method E:

[root@slavedns ~]# dig -x 192.168.1.201



;; Got answer:





;; ANSWER SECTION:

201.1.168.192.in-addr.arpa. 86400 INPTRslavedns.ostechnix.com.








;; SERVER: 192.168.1.200#53(192.168.1.200)

;; WHEN: Sun Mar 3 13:03:39 2013


Method F:

[root@slavedns ~]# dig -x 192.168.1.200



;; Got answer:





;; ANSWER SECTION:

200.1.168.192.in-addr.arpa. 86400 INPTRmasterdns.ostechnix.com.








;; SERVER: 192.168.1.200#53(192.168.1.200)

;; WHEN: Sun Mar 3 13:04:15 2013


Setup DNS Server Step by Step in Centos - Rhel -Scientific Linux

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