Passo-a-passo da instalação de um servidor DNS através do CentOS 6.5/6.4/6.3
DNS, ou Domain Name System, que em português significa Sistema de Nomes de Domínios, são servidores que armazenam listagens de domínios e seus respectivos endereços IPs. É através dele que um IP pode ser associado a um domínio. E como fazer a instalação de um servidor DNS utilizando o CentOS?
Considere o seguinte cenário:
Servidor de DNS Primário:Operating System : CentOS 6.5 server Hostname : masterdns.vpscheap.local IP Address : 192.168.1.100/24Servidor de DNS Secundário:
Operating System : CentOS 6.5 server Hostname : secondarydns.vpscheap.local IP Address : 192.168.1.101/24Cliente:
Operating System : CentOS 6.5 Desktop Hostname : Client.vpscheap.local IP Address : 192.168.1.102/24
E como é feita a instalação? No servidor primário, utilize o comando:
[root@masterdns ~]# yum install bind* -yEntão, é necessário configurar o servidor primário. Adicione as seguintes linhas como apresentado abaixo no exemplo do aquivo named.conf.
[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"vpscheap.local" IN {
type master;
file "forward.vpscheap";
allow-update { none; };
};
zone"1.168.192.in-addr.arpa" IN {
type master;
file "reverse.vpscheap";
allow-update { none; };
};
include "/etc/named.rfc1912.zones";
include "/etc/named.root.key";
Crie zonas de arquivos diretas e reversas no arquivo "/etc/named.conf" para criar uma zona direta, insira forward.vpscheap no arquivo do diretório "/var/named".[root@masterdns ~]# vi /var/named/forward.vpscheap
$TTL 86400
@ IN SOA masterdns.vpscheap.local. root.vpscheap.local. (
2011071001 ;Serial
3600 ;Refresh
1800 ;Retry
604800 ;Expire
86400 ;Minimum TTL
)
@ IN NS masterdns.vpscheap.local.
@ IN NS secondarydns.vpscheap.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
Para criar uma zona direta, insira reverse.vpscheap no arquivo do diretório "/var/named".
[root@masterdns ~]# vi /var/named/reverse.vpscheap
$TTL 86400
@ IN SOA masterdns.vpscheap.local. root.vpscheap.local. (
2011071001 ;Serial
3600 ;Refresh
1800 ;Retry
604800 ;Expire
86400 ;Minimum TTL
)
@ IN NS masterdns.vpscheap.local.
@ IN NS secondarydns.vpscheap.local.
@ IN PTR vpscheap.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.vpscheap.local.
101 IN PTR secondarydns.vpscheap.local.
102 IN PTR client.vpscheap.local.
Inicie o serviço de DNS
[root@masterdns ~]# service named start Starting named: [ OK ] [root@masterdns ~]# chkconfig named on
Faça os ajustes de iptables para permitir que o servidor DNS funcione fora da rede. Insira as linhas apresentadas abaixo no arquivo "/etc/sysconfig/iptables".
[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 COMMITEntão, reinicie as 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 ]Teste as configurações para verificar se não há erros.
[root@masterdns ~]# named-checkconf /etc/named.conf [root@masterdns ~]# named-checkzone vpscheap.local /var/named/forward.vpscheap zone vpscheap.local/IN: loaded serial 2011071001 OK [root@masterdns ~]# named-checkzone vpscheap.local /var/named/reverse.vpscheap zone vpscheap.local/IN: loaded serial 2011071001 OKAgora, teste o servidor DNS.
[root@masterdns ~]# dig masterdns.vpscheap.local ; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6_3.6 <<>> masterdns.vpscheap.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.vpscheap.local.INA ;; ANSWER SECTION: masterdns.vpscheap.local. 86400INA192.168.1.100 ;; AUTHORITY SECTION: vpscheap.local.86400INNSsecondarydns.vpscheap.local. vpscheap.local.86400INNSmasterdns.vpscheap.local. ;; ADDITIONAL SECTION: secondarydns.vpscheap.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 vpscheap.local Server:192.168.1.100 Address:192.168.1.100#53 Name:vpscheap.local Address: 192.168.1.102 Name:vpscheap.local Address: 192.168.1.100 Name:vpscheap.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
Configure o servidor secundário. Abra a configuração principal do arquivo ‘/etc/named.conf’ e insira as linhas baixo.
[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"vpscheap.local" IN {
type slave;
file "slaves/vpscheap.fwd";
masters { 192.168.1.100; };
};
zone"1.168.192.in-addr.arpa" IN {
type slave;
file "slaves/vpscheap.rev";
masters { 192.168.1.100; };
};
include "/etc/named.rfc1912.zones";
include "/etc/named.root.key";
Inicie o serviço de DNS.
[root@secondarydns ~]# service named start Generating /etc/rndc.key: [ OK ] Starting named: [ OK ] [root@secondarydns ~]# chkconfig named onAgora, as zonas diretas e reversas serão automaticamente replicadas do servidor primário para o secundário. Indo para o arquivo ‘/var/named/slaves/’.
[root@secondarydns ~]# ls /var/named/slaves/ vpscheap.fwd vpscheap.rev [root@secondarydns ~]# cat /var/named/slaves/vpscheap.fwd $ORIGIN . $TTL 86400; 1 day vpscheap.localIN SOAmasterdns.vpscheap.local. root.vpscheap.local. ( 2011071001 ; serial 3600 ; refresh (1 hour) 1800 ; retry (30 minutes) 604800 ; expire (1 week) 86400 ; minimum (1 day) ) NS masterdns.vpscheap.local. NS secondarydns.vpscheap.local. A192.168.1.100 A192.168.1.101 A192.168.1.102 $ORIGIN vpscheap.local. clientA192.168.1.102 masterdnsA192.168.1.100 secondarydnsA192.168.1.101 [root@secondarydns ~]# cat /var/named/slaves/vpscheap.rev $ORIGIN . $TTL 86400; 1 day 1.168.192.in-addr.arpaIN SOAmasterdns.vpscheap.local. root.vpscheap.local. ( 2011071001 ; serial 3600 ; refresh (1 hour) 1800 ; retry (30 minutes) 604800 ; expire (1 week) 86400 ; minimum (1 day) ) NS masterdns.vpscheap.local. NS secondarydns.vpscheap.local. PTRvpscheap.local. $ORIGIN 1.168.192.in-addr.arpa. 100PTRmasterdns.vpscheap.local. 101PTRsecondarydns.vpscheap.local. 102PTRclient.vpscheap.local. clientA192.168.1.102 masterdnsA192.168.1.100 secondarydnsA192.168.1.101Adicionar os detalhes do servidor em todos os sistemas
[root@secondarydns ~]# vi /etc/resolv.conf # Generated by NetworkManager search ostechnix.com nameserver 192.168.1.100 nameserver 192.168.1.101 nameserver 8.8.8.8Teste o servidor DNS novamente
[root@secondarydns ~]# dig masterdns.vpscheap.local ; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6_3.6 <<>> masterdns.vpscheap.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.vpscheap.local.INA ;; ANSWER SECTION: masterdns.vpscheap.local. 86400INA192.168.1.100 ;; AUTHORITY SECTION: vpscheap.local.86400INNSmasterdns.vpscheap.local. vpscheap.local.86400INNSsecondarydns.vpscheap.local. ;; ADDITIONAL SECTION: secondarydns.vpscheap.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.vpscheap.local ; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6_3.6 <<>> secondarydns.vpscheap.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.vpscheap.local.INA ;; ANSWER SECTION: secondarydns.vpscheap.local. 86400 INA192.168.1.101 ;; AUTHORITY SECTION: vpscheap.local.86400INNSmasterdns.vpscheap.local. vpscheap.local.86400INNSsecondarydns.vpscheap.local. ;; ADDITIONAL SECTION: masterdns.vpscheap.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 vpscheap.local Server:192.168.1.100 Address:192.168.1.100#53 Name:vpscheap.local Address: 192.168.1.101 Name:vpscheap.local Address: 192.168.1.102 Name:vpscheap.local Address: 192.168.1.100
Configuração no servidor do cliente
Adicione os detalhes apresentados no arquivo ‘/etc/resolv.conf’ nos sistemas de todos os clientes.[root@client vpscheap]# vi /etc/resolv.conf # Generated by NetworkManager search vpscheap.local nameserver 192.168.1.100 nameserver 192.168.1.101 nameserver 8.8.8.8Teste o servidor DNS.
[root@client vpscheap]# dig masterdns.vpscheap.local ; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6 <<>> masterdns.vpscheap.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.vpscheap.local.INA ;; ANSWER SECTION: masterdns.vpscheap.local. 86400INA192.168.1.100 ;; AUTHORITY SECTION: vpscheap.local.86400INNSmasterdns.vpscheap.local. vpscheap.local.86400INNSsecondarydns.vpscheap.local. ;; ADDITIONAL SECTION: secondarydns.vpscheap.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 vpscheap]# dig secondarydns.vpscheap.local ; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6 <<>> secondarydns.vpscheap.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.vpscheap.local.INA ;; ANSWER SECTION: secondarydns.vpscheap.local. 86400 INA192.168.1.101 ;; AUTHORITY SECTION: vpscheap.local.86400INNSsecondarydns.vpscheap.local. vpscheap.local.86400INNSmasterdns.vpscheap.local. ;; ADDITIONAL SECTION: masterdns.vpscheap.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 vpscheap]# dig client.vpscheap.local ; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6 <<>> client.vpscheap.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.vpscheap.local.INA ;; ANSWER SECTION: client.vpscheap.local.86400INA192.168.1.102 ;; AUTHORITY SECTION: vpscheap.local.86400INNSmasterdns.vpscheap.local. vpscheap.local.86400INNSsecondarydns.vpscheap.local. ;; ADDITIONAL SECTION: masterdns.vpscheap.local. 86400INA192.168.1.100 secondarydns.vpscheap.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 vpscheap]# nslookup vpscheap.local Server:192.168.1.100 Address:192.168.1.100#53 Name:vpscheap.local Address: 192.168.1.102 Name:vpscheap.local Address: 192.168.1.100 Name:vpscheap.local Address: 192.168.1.101Agora os servidores estão prontos!
