Oracle Linux 7 Configure DNS

Oracle Linux 7.1配置DNS服务
一.安装DNS需要的软件包

# yum install bind-libs bind bind-utils

二.编辑named.conf文件
在编辑前先复制一份named.conf文件

[root@jytest1 ~]# cp /etc/named.conf /etc/named.conf.backup


[root@jytest1 ~]# 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 { any; };--将127.0.0.1修改成any
        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     { any; };--将127.0.0.1修改成any

        /* 
         - If you are building an AUTHORITATIVE DNS server, do NOT enable recursion.
         - If you are building a RECURSIVE (caching) DNS server, you need to enable 
           recursion. 
         - If your recursive DNS server has a public IP address, you MUST enable access 
           control to limit queries to your legitimate users. Failing to do so will
           cause your server to become part of large scale DNS amplification 
           attacks. Implementing BCP38 within your network would greatly
           reduce such attack surface 
        */
        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";

        pid-file "/run/named/named.pid";
        session-keyfile "/run/named/session.key";
};

logging {
        channel default_debug {
                file "data/named.run";
                severity dynamic;
        };
};

zone "." IN {
        type hint;
        file "named.ca";
};
include "/etc/named.rfc1912.zones";
include "/etc/named.root.key";

三.配置host.conf

[root@jytest1 ~]# cat /etc/host.conf
multi on

该文件指定如何解析主机名。Linux通过解析器库来获得主机名对应的IP地址。下面是一个“/etc/host.conf”的示例:
order bind,hosts
multi on
nospoof on
“order bind,hosts”指定主机名查询顺序,这里规定先使用DNS来解析域名,然后再查询“/etc/hosts”文件(也可以相反)。
“multi on”指定是否“/etc/hosts”文件中指定的主机可以有多个地址,拥有多个IP地址的主机一般称为多穴主机。
“nospoof on”指不允许对该服务器进行IP地址欺骗。IP欺骗是一种攻击系统安全的手段,通过把IP地址伪装成别的计算机,来取得其它计算机的信任。

四.修改/etc/named.rfc1912.zones

[root@jytest1 ~]# cp /etc/named.rfc1912.zones /etc/named.rfc1912.zones.backup
[root@jytest1 ~]# vi /etc/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
// and http://www.ietf.org/internet-drafts/draft-ietf-dnsop-default-local-zones-02.txt
// (c)2007 R W Franks
//
// See /usr/share/doc/bind*/sample/ for example named configuration files.
//

zone "localhost.localdomain" IN {
        type master;
        file "named.localhost";
        allow-update { none; };
};

zone "localhost" IN {
        type master;
        file "named.localhost";
        allow-update { none; };
};

zone "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa" IN {
        type master;
        file "named.loopback";
        allow-update { none; };
};

zone "1.0.0.127.in-addr.arpa" IN {
        type master;
        file "named.loopback";
        allow-update { none; };
};

zone "0.in-addr.arpa" IN {
        type master;
        file "named.empty";
        allow-update { none; };
};

--下面为增加的内容,jybd.net.forward为正向解析,jydba.net.reverse为反向解析
zone "jydba.net" IN {
        type master;
        file "jydba.net.forward";
        allow-update { none; };
};

zone "130.138.10.in-addr.arpa" IN {
        type master;
        file "jydba.net.reverse";
        allow-update { none; };
};
"/etc/named.rfc1912.zones" 54L, 1171C written

五.修改具体的zone配置文件

[root@jytest1 named]# cd /var/named
[root@jytest1 named]# cp named.localhost jydba.net.forward
[root@jytest1 named]# cp named.loopback jydba.net.reverse

[root@jytest1 named]# vi jydba.net.forward
$TTL 1D
@       IN SOA  @ root.jydba.net. (
                                        0       ; serial
                                        1D      ; refresh
                                        1H      ; retry
                                        1W      ; expire
                                        3H )    ; minimum
        NS      @
        A       10.138.130.171
        AAAA    ::1

jytest1              A            10.138.130.171
jytest2              A            10.138.130.172
jytest1-vip          A            10.138.130.175
jytest2-vip          A            10.138.130.176
jytest-scan          A            10.138.130.177
jytest-scan          A            10.138.130.178
jytest-scan          A            10.138.130.179


[root@jytest1 named]# vi jydba.net.reverse
$TTL 1D
@       IN SOA  @ root.jydba.net. (
                                        0       ; serial
                                        1D      ; refresh
                                        1H      ; retry
                                        1W      ; expire
                                        3H )    ; minimum
        NS      @
        A       10.138.130.171
        AAAA    ::1
        PTR     localhost.

171           PTR     jytest1
172           PTR     jytest2
175           PTR     jytest1-vip
176           PTR     jytest2-vip
177           PTR     jytest-scan
178           PTR     jytest-scan
179           PTR     jytest-scan

六.配置resolv.conf

[root@jytest1 named]# cat /etc/resolv.conf
# Generated by NetworkManager
search jydba.net


# No nameservers found; try putting DNS servers into your
# ifcfg files in /etc/sysconfig/network-scripts like so:
#
# DNS1=xxx.xxx.xxx.xxx
# DNS2=xxx.xxx.xxx.xxx
# DOMAIN=lab.foo.com bar.foo.com
search jydba.net
nameserver       10.138.130.171

七.测试

[root@jytest1 named]# dig -x 10.138.130.172

; < <>> DiG 9.9.4-RedHat-9.9.4-18.el7 < <>> -x 10.138.130.172
;; global options: +cmd
;; Got answer:
;; ->>HEADER< <- opcode: QUERY, status: REFUSED, id: 20870
;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1
;; WARNING: recursion requested but not available

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;172.130.138.10.in-addr.arpa.   IN      PTR

;; Query time: 6 msec
;; SERVER: 10.138.130.171#53(10.138.130.171)
;; WHEN: Fri Mar 17 19:15:47 CST 2017
;; MSG SIZE  rcvd: 56




[root@jytest1 named]# service named restart
Redirecting to /bin/systemctl restart  named.service
[root@jytest1 named]# nslookup jytest1
Server:         10.138.130.171
Address:        10.138.130.171#53

** server can't find jytest1: SERVFAIL

上面出现错误,server can't find jytest1: SERVFAIL,错误信息是因为之前创建文件时使用的是root用户,将这些创建的文件修改为named用户与组。

[root@jytest1 named]# ls -lrt
total 32
-rw-r-----. 1 root  named  152 Jun 21  2007 named.localhost
-rw-r-----. 1 root  named  168 Dec 15  2009 named.loopback
-rw-r-----. 1 root  named  152 Dec 15  2009 named.empty
-rw-r-----. 1 root  named 2076 Jan 28  2013 named.ca
drwxrwx---. 2 root  named    6 Mar  6  2015 dyndb-ldap
drwxrwx---. 2 named named    6 Mar  6  2015 slaves
drwxr-x---. 7 root  named   56 Nov  5 11:03 chroot
-rw-r-----  1 root  named  728 Mar 17 18:45 named.jydba
-rw-r--r--  1 root  root   829 Mar 17 18:45 jydba.zone
drwxrwx---. 2 named named   22 Mar 17 18:45 data
-rw-r-----  1 root  root   503 Mar 17 19:13 jydba.net.forward
-rw-r-----  1 root  root   406 Mar 17 19:15 jydba.net.reverse
drwxrwx---. 2 named named   58 Mar 17 19:16 dynamic
[root@jytest1 named]# chown -R named:named jydba*
[root@jytest1 named]# ls -lrt
total 32
-rw-r-----. 1 root  named  152 Jun 21  2007 named.localhost
-rw-r-----. 1 root  named  168 Dec 15  2009 named.loopback
-rw-r-----. 1 root  named  152 Dec 15  2009 named.empty
-rw-r-----. 1 root  named 2076 Jan 28  2013 named.ca
drwxrwx---. 2 root  named    6 Mar  6  2015 dyndb-ldap
drwxrwx---. 2 named named    6 Mar  6  2015 slaves
drwxr-x---. 7 root  named   56 Nov  5 11:03 chroot
-rw-r-----  1 root  named  728 Mar 17 18:45 named.jydba
-rw-r--r--  1 named named  829 Mar 17 18:45 jydba.zone
drwxrwx---. 2 named named   22 Mar 17 18:45 data
-rw-r-----  1 named named  503 Mar 17 19:13 jydba.net.forward
-rw-r-----  1 named named  406 Mar 17 19:15 jydba.net.reverse
drwxrwx---. 2 named named   58 Mar 17 19:16 dynamic
[root@jytest1 named]# systemctl restart  named.service
[root@jytest1 named]# nslookup jytest1
Server:         10.138.130.171
Address:        10.138.130.171#53

Name:   jytest1.jydba.net
Address: 10.138.130.171

[root@jytest1 named]# nslookup jytest1.jydba.net
Server:         10.138.130.171
Address:        10.138.130.171#53

Name:   jytest1.jydba.net
Address: 10.138.130.171

[root@jytest1 named]# nslookup jytest2-priv.jydba.net
Server:         10.138.130.171
Address:        10.138.130.171#53

** server can't find jytest2-priv.jydba.net: NXDOMAIN

[root@jytest1 named]# nslookup jytest2-vip.jydba.net
Server:         10.138.130.171
Address:        10.138.130.171#53

Name:   jytest2-vip.jydba.net
Address: 10.138.130.176

[root@jytest1 named]# nslookup jytest-scan.jydba.net
Server:         10.138.130.171
Address:        10.138.130.171#53

Name:   jytest-scan.jydba.net
Address: 10.138.130.178
Name:   jytest-scan.jydba.net
Address: 10.138.130.179
Name:   jytest-scan.jydba.net
Address: 10.138.130.177

[root@jytest1 named]# nslookup 10.138.130.179
Server:         10.138.130.171
Address:        10.138.130.171#53

179.130.138.10.in-addr.arpa     name = jytest-scan.130.138.10.in-addr.arpa.

通过测试可以看到DNS通过正向与反向解析都是正常的,说明配置成功。

注意:
对于Linux 使用NetworkManager来控制网络的操作系统,当主机重启之前/etc/resolv.conf文件可能会被重写。如果发生这种情况,需要对相应的网卡配置文件增加以下记录
对于Oracle Linux 6修改类似文件 /etc/sysconfig/network-scripts/ifcfg-eth0 (ifcfg-eth1 etc.)
对于Oracle Linux 7修改类似文/etc/sysconfig/network-scripts/ifcfg-ens160 (ifcfg-ens34 etc.)
DNS1=10.138.130.171
DOMAIN=jydba.net

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