DNS服务器

目标：

• 搭建DNS服务器，接收所有DNS请求（ipv4）
• 针对指定域名mynginx.com，解析到192.168.0.113

环境：

HostName	Host	System	Service
learn-4	192.168.0.112	CentOS 7.6	DNS-Server-Master
learn-5	192.168.0.113	CentOS 7.6	DNS-Client 、Nginx
learn-6	192.168.0.116	CentOS 7.6	DNS-Server-Slave

搭建DNS服务器

DNS服务使用的是UDP协议

协议端口：53

DNS服务器端

安装bind

[root@learn-4 ~]# yum -y install bind bind-chroot bind-utils
# 安装完成后，可以看到以下两个目录生成了对应的文件
/etc/named.conf # BIND服务的配置文件
/var/named/     # DNS解析需要的zone文件列表

修改配置文件

[root@learn-4 ~]# vim /etc/named.conf

options {
		# 监听来自于所有打到53端口的请求
        listen-on port 53 { 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";
        recursing-file  "/var/named/data/named.recursing";
        secroots-file   "/var/named/data/named.secroots";
        # 允许来自任意host的DNS查询
        allow-query     { any; };

启动服务

[root@learn-4 ~]# systemctl start named
[root@learn-4 ~]# systemctl enable named

Client端

修改域名服务器为DNS服务器的IP地址

[root@learn-5 ~]# cat /etc/resolv.conf
# Generated by NetworkManager
nameserver 192.168.0.112

主域名服务器搭建

服务器端

创建一个域名解析记录的数据文件，自己添加 A 记录，CNAME记录等

[root@learn-4 ~]# vim /var/named/mynginx.com.zone
$TTL 1D
@       IN SOA  @ rname.invalid. (
                                        0       ; serial
                                        1D      ; refresh
                                        1H      ; retry
                                        1W      ; expire
                                        3H )    ; minimum
        NS      @
        A       192.168.0.113
www     A       192.168.0.113
git     A       192.168.0.113
test    CNAME   git

修改数据文件的拥有者和组权限

[root@learn-4 ~]# chown -R root:named /var/named/mynginx.com.zone

修改配置文件/etc/named.conf或者/etc/named.rfc1912.zones均可

[root@learn-4 ~]# vim /etc/named.rfc1912.zones

zone "mynginx.com" IN {
        type master;
        file "mynginx.com.zone";
        allow-update { none; };
};

检查配置

# 检查配置文件
[root@learn-4 ~]# named-checkconf
# 检查数据文件
[root@learn-4 ~]# named-checkzone mynginx.com /var/named/mynginx.com.zone
# 刷新服务(如果刷新失败，可通过 /var/log/messages 里的日志文件进行排错)
[root@learn-4 ~]# systemctl restart named

Client端

• 192.168.0.113 安装nginx服务

[root@learn-5 ~]# rpm -Uvh  http://nginx.org/packages/centos/7/noarch/RPMS/nginx-release-centos-7-0.el7.ngx.noarch.rpm
[root@learn-5 ~]# yum install nginx -y
[root@learn-5 ~]# systemctl start nginx

测试域名解析过程

# yum -y install bind-utils
[root@learn-5 ~]# nslookup www.mynginx.com
Server:         192.168.0.112
Address:        192.168.0.112#53

Name:   www.mynginx.com
Address: 192.168.0.113

[root@learn-5 ~]# nslookup test.mynginx.com
Server:         192.168.0.112
Address:        192.168.0.112#53

test.mynginx.com        canonical name = git.mynginx.com.
Name:   git.mynginx.com
Address: 192.168.0.113

ping测试

[root@learn-5 ~]# ping www.mynginx.com
PING www.mynginx.com (192.168.0.113) 56(84) bytes of data.
64 bytes from learn-5 (192.168.0.113): icmp_seq=1 ttl=64 time=0.016 ms
64 bytes from learn-5 (192.168.0.113): icmp_seq=2 ttl=64 time=0.079 ms
64 bytes from learn-5 (192.168.0.113): icmp_seq=3 ttl=64 time=0.046 ms
64 bytes from learn-5 (192.168.0.113): icmp_seq=4 ttl=64 time=0.041 ms
64 bytes from learn-5 (192.168.0.113): icmp_seq=5 ttl=64 time=0.030 ms

日志

相关日志记录在 /var/named/data/named.run 文件中

DNS从服务器

有时DNS服务器需要使用多副本的方式，BIND也提供了主-从服务器的机制方便多个服务器之间进行同步。

• 192.168.0.116 DNS-server-slave

部署BIND

[root@learn-6 ~]# yum -y install bind bind-chroot bind-utils

编辑配置

[root@learn-6 ~]# vim /etc/named.conf

options {
		# 监听来自于所有打到53端口的请求
        listen-on port 53 { 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";
        recursing-file  "/var/named/data/named.recursing";
        secroots-file   "/var/named/data/named.secroots";
        # 允许来自任意host的DNS查询
        allow-query     { any; };
  
  
[root@learn-6 ~]# vim /etc/named.rfc1912.zones
# 新增配置
zone "mynginx.com" IN {
        type slave;
        masters { 192.168.0.112; };
        file "slaves/mynginx.com.zone";
};

• 192.168.0.112 DNS-server-master

将数据文件拷贝至 /var/named/slaves/ 目录下

[root@learn-4 ~]# cp /var/named/mynginx.com.zone /var/named/slaves/

• 192.168.0.116 DNS-server-slave

启动named服务

[root@learn-6 ~]# systemctl start named
[root@learn-6 ~]# systemctl enable named

此时slave节点会自动同步master节点上的数据文件（slaves/mynginx.com.zone）至对应目录

• 192.168.0.113 DNS-Client

修改域名服务器为DNS从服务器的IP地址

[root@learn-5 ~]# cat /etc/resolv.conf
# Generated by NetworkManager
nameserver 192.168.0.116

解析验证

[root@learn-6 ~]# vim /etc/resolv.conf
nameserver 192.168.0.116

[root@learn-6 ~]# nslookup www.mynginx.com
Server:         192.168.0.116
Address:        192.168.0.116#53

Name:   www.mynginx.com
Address: 192.168.0.113

[root@learn-6 ~]# nslookup test.mynginx.com
Server:         192.168.0.116
Address:        192.168.0.116#53

test.mynginx.com        canonical name = git.mynginx.com.
Name:   git.mynginx.com
Address: 192.168.0.113

[root@learn-6 ~]# nslookup git.mynginx.com
Server:         192.168.0.116
Address:        192.168.0.116#53

Name:   git.mynginx.com
Address: 192.168.0.113

ping验证

[root@learn-6 ~]# ping www.mynginx.com
PING www.mynginx.com (192.168.0.113) 56(84) bytes of data.
64 bytes from learn-5 (192.168.0.113): icmp_seq=1 ttl=64 time=0.015 ms
64 bytes from learn-5 (192.168.0.113): icmp_seq=2 ttl=64 time=0.063 ms
64 bytes from learn-5 (192.168.0.113): icmp_seq=3 ttl=64 time=0.028 ms