Liunx 配置dns

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从 Oracle 11gR2 开始，引入 SCAN(Single Client Access Name) IP 的概念，相当于在客户端和数据库之间增加一层虚拟的网络服务层，即是 SCAN IP 和 SCAP IP Listener。在客户端的 tnsnames.ora 配置文件中，只需要配置 SCAN IP 的配置信息即可，客户端通过 SCAN IP、SCAN IP Listener 来访问数据库。同之前各版本的 RAC 相比，使用 SCAN IP 的好处就是，当后台 RAC 数据库添加、删除节点时，客户端配置信息无需修改。可以通过配置 DNS 服

务器或 GNS 来配置 SCAN，我们这里以 DNS 为例来进行配置。

首先先介绍一下环境：

DNS服务器环境如下(非rac节点)

[root@localhost ~]# [root@localhost ~]# ifconfigeth0      Link encap:Ethernet  HWaddr 00:0C:29:72:C0:1E            inet addr:192.168.2.128  Bcast:192.168.2.255  Mask:255.255.255.0          inet6 addr: fe80::20c:29ff:fe72:c01e/64 Scope:Link          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1          RX packets:7836 errors:0 dropped:0 overruns:0 frame:0          TX packets:2127 errors:0 dropped:0 overruns:0 carrier:0          collisions:0 txqueuelen:1000           RX bytes:720365 (703.4 KiB)  TX bytes:278821 (272.2 KiB)lo        Link encap:Local Loopback            inet addr:127.0.0.1  Mask:255.0.0.0          inet6 addr: ::1/128 Scope:Host          UP LOOPBACK RUNNING  MTU:16436  Metric:1          RX packets:1525 errors:0 dropped:0 overruns:0 frame:0          TX packets:1525 errors:0 dropped:0 overruns:0 carrier:0          collisions:0 txqueuelen:0           RX bytes:4231012 (4.0 MiB)  TX bytes:4231012 (4.0 MiB)[root@localhost ~]# cat /etc/hosts# Do not remove the following line, or various programs# that require network functionality will fail.127.0.0.1               localhost.localdomain localhost::1             localhost6.localdomain6 localhost6[root@localhost ~]# [root@localhost ~]# hostnamelocalhost.localdomain[root@localhost ~]#

Oracle Rac其中一个节点环境如下

[root@racr1 ~]# [root@racr1 ~]# ifconfigeth0      Link encap:Ethernet  HWaddr 00:0C:29:A2:C0:78            inet addr:192.168.2.11  Bcast:192.168.2.255  Mask:255.255.255.0          inet6 addr: fe80::20c:29ff:fea2:c078/64 Scope:Link          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1          RX packets:3338 errors:0 dropped:0 overruns:0 frame:0          TX packets:429 errors:0 dropped:0 overruns:0 carrier:0          collisions:0 txqueuelen:1000           RX bytes:307857 (300.6 KiB)  TX bytes:50883 (49.6 KiB)eth1      Link encap:Ethernet  HWaddr 00:0C:29:A2:C0:82            inet addr:10.10.27.11  Bcast:10.10.27.255  Mask:255.255.255.0          inet6 addr: fe80::20c:29ff:fea2:c082/64 Scope:Link          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1          RX packets:3572 errors:0 dropped:0 overruns:0 frame:0          TX packets:53 errors:0 dropped:0 overruns:0 carrier:0          collisions:0 txqueuelen:1000           RX bytes:307775 (300.5 KiB)  TX bytes:7022 (6.8 KiB)lo        Link encap:Local Loopback            inet addr:127.0.0.1  Mask:255.0.0.0          inet6 addr: ::1/128 Scope:Host          UP LOOPBACK RUNNING  MTU:16436  Metric:1          RX packets:1395 errors:0 dropped:0 overruns:0 frame:0          TX packets:1395 errors:0 dropped:0 overruns:0 carrier:0          collisions:0 txqueuelen:0           RX bytes:2813005 (2.6 MiB)  TX bytes:2813005 (2.6 MiB)[root@racr1 ~]# cat /etc/hosts# Do not remove the following line, or various programs# that require network functionality will fail.127.0.0.1       localhost::1             localhost6.localdomain6 localhost6# public192.168.2.11 racr1.localdomain  racr1192.168.2.12 racr2.localdomain  racr2# private10.10.27.21  racr1-priv.localdomain  racr1-priv10.10.27.22  racr2-priv.localdomain  racr2-priv# vip192.168.2.13  racr1-vip.localdomain  racr1-vip192.168.2.14  racr2-vip.localdomain  racr2-vip#scan-ip192.168.2.203  scan-cluster.localdomain  scan-cluster[root@racr1 ~]# hostnameracr1.localdomain[root@racr1 ~]#

步骤一：安装dns软件在dns服务器

[root@localhost ~]# cd dnslib/[root@localhost dnslib]# lltotal 1112-rw-r--r-- 1 root root 1015531 Jun 24 14:34 bind-9.3.6-4.P1.el5_4.2.x86_64.rpm-rw-r--r-- 1 root root   45360 Jun 24 14:34 bind-chroot-9.3.6-4.P1.el5_4.2.x86_64.rpm-rw-r--r-- 1 root root   62251 Jun 24 14:35 caching-nameserver-9.3.6-4.P1.el5_4.2.x86_64.rpm[root@localhost dnslib]# [root@localhost dnslib]# [root@localhost dnslib]# rpm -ivh bind-9.3.6-4.P1.el5_4.2.x86_64.rpm warning: bind-9.3.6-4.P1.el5_4.2.x86_64.rpm: Header V3 DSA signature: NOKEY, key ID 1e5e0159Preparing...                ########################################### [100%]   1:bind                   ########################################### [100%][root@localhost dnslib]# [root@localhost dnslib]# rpm -ivh bind-chroot-9.3.6-4.P1.el5_4.2.x86_64.rpm warning: bind-chroot-9.3.6-4.P1.el5_4.2.x86_64.rpm: Header V3 DSA signature: NOKEY, key ID 1e5e0159Preparing...                ########################################### [100%]   1:bind-chroot            ########################################### [100%][root@localhost dnslib]# [root@localhost dnslib]# rpm -ivh caching-nameserver-9.3.6-4.P1.el5_4.2.x86_64.rpmwarning: caching-nameserver-9.3.6-4.P1.el5_4.2.x86_64.rpm: Header V3 DSA signature: NOKEY, key ID 1e5e0159Preparing...                ########################################### [100%]   1:caching-nameserver     ########################################### [100%][root@localhost dnslib]# [root@localhost dnslib]#

安装完毕后，进入软件安装目录查看

[root@localhost dnslib]# cd /var/named/chroot/etc/[root@localhost etc]# lltotal 16-rw-r--r-- 1 root root   405 Jun 24  2014 localtime-rw-r----- 1 root named 1230 Jan 21  2010 named.caching-nameserver.conf-rw-r----- 1 root named  955 Jan 21  2010 named.rfc1912.zones-rw-r----- 1 root named  113 Jun 24 14:36 rndc.key[root@localhost etc]# [root@localhost etc]#

步骤二：准备配置文件named.conf

[root@localhost etc]# [root@localhost etc]# cp -p named.caching-nameserver.conf named.conf[root@localhost etc]# [root@localhost etc]# lltotal 20-rw-r--r-- 1 root root   405 Jun 24  2014 localtime-rw-r----- 1 root named 1230 Jan 21  2010 named.caching-nameserver.conf-rw-r----- 1 root named 1230 Jan 21  2010 named.conf-rw-r----- 1 root named  955 Jan 21  2010 named.rfc1912.zones-rw-r----- 1 root named  113 Jun 24 14:36 rndc.key[root@localhost etc]# [root@localhost etc]#

准备配置文件 named.conf 从模板里面直接复制，查看修改后的named.conf

[root@localhost etc]# cat named.conf//// named.caching-nameserver.conf//// Provided by Red Hat caching-nameserver 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.//// DO NOT EDIT THIS FILE - use system-config-bind or an editor// to create named.conf - edits to this file will be lost on // caching-nameserver package upgrade.//options {        listen-on port 53 { 127.0.0.1; };        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";        // Those options should be used carefully because they disable port        // randomization        // query-source    port 53;        // query-source-v6 port 53;        allow-query     { localhost; };        allow-query-cache { localhost; };};logging {        channel default_debug {                file "data/named.run";                severity dynamic;        };};view localhost_resolver {        match-clients      { localhost; };        match-destinations { localhost; };        recursion yes;        include "/etc/named.rfc1912.zones";};[root@localhost etc]#

为简单起见，将该文件中的 127.0.0.1、localhost 全部修改成 any，且修改时，需要注意左右两边留空格。

步骤三：配置 Zone 文件

配置 Zone 文件，修改/var/named/chroot/etc/named.rfc1912.zones 文件
配置 Zone 的目的是为了解析 SCAN IP，在该文件末尾添加以下反向 Zone：

zone "2.168.192.in-addr.arpa." IN {        type master;        file "2.168.192.in-addr.arpa";        allow-update { none; };};

修改后查看文件

[root@localhost etc]# vi named.rfc1912.zones// named.rfc1912.zones://// Provided by Red Hat caching-nameserver package//// ISC BIND named zone configuration for zones recommended by// RFC 1912 section 4.1 : localhost TLDs and address zones//// See /usr/share/doc/bind*/sample/ for example named configuration files.//zone "." IN {        type hint;        file "named.ca";};zone "localdomain" IN {        type master;        file "localdomain.zone";        allow-update { none; };};zone "localhost" IN {        type master;        file "localhost.zone";        allow-update { none; };};zone "0.0.127.in-addr.arpa" IN {        type master;        file "named.local";        allow-update { none; };};zone "0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa" IN {        type master;        file "named.ip6.local";        allow-update { none; };};zone "255.in-addr.arpa" IN {        type master;        file "named.broadcast";        allow-update { none; };};zone "0.in-addr.arpa" IN {        type master;        file "named.zero";        allow-update { none; };};zone "2.168.192.in-addr.arpa." IN {        type master;        file "2.168.192.in-addr.arpa";        allow-update { none; };};

说明：正常情况下还应该配置正向 Zone 文件。这里，我们的 RAC 双节点 node1、 node2的域名 domain 都设置为 localdomain ，而默认情况下，该配置文件(/var/named/chroot/etc/named.rfc1912.zones)的第 15 行到第 20 行中已经自带下述正向 Zone 文件配置信息，所以无需再添加。

还有这个文件的名字和IP要对应，因为这里节点1的public网卡在192.168.2.*端，所有文件名字要2.168.198。

步骤四：配置正、反向解析数据库文件

这个数据库文件就是named.rfc1912.zones文件里面每个zone里面的file属性。现在这2个文件是没有的，我们要手工的创建

localdomain.zone这个文件已经存在了，我们直接修改就好了，这个文件是正向解析数据库文件。

[root@localhost etc]# cd /var/named/chroot/var/named/[root@localhost named]# lltotal 36drwxrwx--- 2 named named 4096 Aug 26  2004 data-rw-r----- 1 root  named  198 Jan 21  2010 localdomain.zone-rw-r----- 1 root  named  195 Jan 21  2010 localhost.zone-rw-r----- 1 root  named  427 Jan 21  2010 named.broadcast-rw-r----- 1 root  named 1892 Jan 21  2010 named.ca-rw-r----- 1 root  named  424 Jan 21  2010 named.ip6.local-rw-r----- 1 root  named  426 Jan 21  2010 named.local-rw-r----- 1 root  named  427 Jan 21  2010 named.zerodrwxrwx--- 2 named named 4096 Jul 27  2004 slaves[root@localhost named]# [root@localhost named]# [root@localhost named]# cat localdomain.zone $TTL    86400@               IN SOA  localhost root (                                        42              ; serial (d. adams)                                        3H              ; refresh                                        15M             ; retry                                        1W              ; expiry                                        1D )            ; minimum                IN NS           localhostlocalhost       IN A            127.0.0.1scan-cluster IN A 192.168.2.203 #直接添加这行，和节点1的hosts文件对应上[root@localhost named]# [root@localhost named]#

继续配置反向数据文件2.168.192.in-addr.arpa

[root@localhost etc]# cd /var/named/chroot/var/named/[root@localhost named]# cp -p named.local 2.168.192.in-addr.arpa[root@localhost named]# [root@localhost named]# [root@localhost named]# lltotal 40-rw-r----- 1 root  named  426 Jan 21  2010 2.168.192.in-addr.arpadrwxrwx--- 2 named named 4096 Aug 26  2004 data-rw-r----- 1 root  named  198 Jan 21  2010 localdomain.zone-rw-r----- 1 root  named  195 Jan 21  2010 localhost.zone-rw-r----- 1 root  named  427 Jan 21  2010 named.broadcast-rw-r----- 1 root  named 1892 Jan 21  2010 named.ca-rw-r----- 1 root  named  424 Jan 21  2010 named.ip6.local-rw-r----- 1 root  named  426 Jan 21  2010 named.local-rw-r----- 1 root  named  427 Jan 21  2010 named.zerodrwxrwx--- 2 named named 4096 Jul 27  2004 slaves[root@localhost named]# [root@localhost named]# [root@localhost named]# cat 2.168.192.in-addr.arpa $TTL    86400@       IN      SOA     localhost. root.localhost.  (                                      1997022700 ; Serial                                      28800      ; Refresh                                      14400      ; Retry                                      3600000    ; Expire                                      86400 )    ; Minimum        IN      NS      localhost.1       IN      PTR     localhost.203 IN PTR scan-cluster.localdomain.[root@localhost named]#

对我们来说，只有添加最后的一行，这里的203对应节点1里面的scan-ip(192.168.2.203)的203,注意在can-cluster.localdomain.的符合"."。不能少啊

步骤五：启动DNS服务器

[root@localhost named]# /etc/init.d/named startStarting named: [  OK  ][root@localhost named]# [root@localhost named]# /etc/init.d/named statusnumber of zones: 7debug level: 0xfers running: 0xfers deferred: 0soa queries in progress: 0query logging is OFFrecursive clients: 0/1000tcp clients: 0/100server is up and runningnamed (pid  9143) is running...[root@localhost named]#

步骤六：每个节点配置DNS客户端

[root@racr1 media]# [root@racr1 media]# cat /etc/resolv.confsearch localdomainnameserver 192.168.2.128[root@racr1 media]# [root@racr1 media]# [root@racr1 media]# nslookup  scan-clusterServer:         192.168.2.128Address:        192.168.2.128#53Name:   scan-cluster.localdomainAddress: 192.168.2.203[root@racr1 media]# nslookup scan-cluster.localdomainServer:         192.168.2.128Address:        192.168.2.128#53Name:   scan-cluster.localdomainAddress: 192.168.2.203[root@racr1 media]# nslookup 192.168.2.203Server:         192.168.2.128Address:        192.168.2.128#53203.2.168.192.in-addr.arpa      name = scan-cluster.localdomain.[root@racr1 media]#

创建和修改/etc/resolv.conf文件，添加上面2行，192.168.2.128是DNS服务器的地址，至于192.168.2.203只是我们虚拟出来的，大家要分清楚。

我其实对DNS也不是太了解，这个是我自己总结的一种方法，稍后我会安装oracle11.2 rac上面验证这个配置方法。

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