本文已参与「新人创作礼」活动， 一起开启掘金创作之路。
1.实战案例：实现DNS forward（缓存）服务器
1.1 实验目的
搭建DNS转发（缓存）服务器
1.2 环境要求
需要四台主机
DNS主服务器：172.31.1.8
DNS只缓存服务器：172.31.1.18
web服务器：172.31.0.7
DNS客户端：172.31.0.17
1.3 前提准备
关闭SElinux
关闭防火墙
时间同步
1.4 实现步骤
1.4.1 实现主DNS服务器
[root@rocky8 ~]# dnf -y install bind
[root@rocky8 ~]# vim /etc/named.conf
options {
// listen-on port 53 { 127.0.0.1; }; #注释此行
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";
secroots-file "/var/named/data/named.secroots";
recursing-file "/var/named/data/named.recursing";
// allow-query { localhost; }; #注释此行
#关闭加密验证
dnssec-enable no;
dnssec-validation no
[root@rocky8 ~]# vim /etc/named.rfc1912.zones
#加上下面这段
zone "raymonds.cc" {
type master;
file "raymonds.cc.zone";
};
[root@rocky8 ~]# cp -p /var/named/named.localhost /var/named/raymonds.cc.zone
#如果没有-p，需要改权限。chgrp named raymonds.cc.zone
[root@rocky8 ~]# vim /var/named/raymonds.cc.zone
$TTL 1D
@ IN SOA master admin.raymonds.cc. (
1 ; serial
1D ; refresh
1H ; retry
1W ; expire
3H ) ; minimum
NS master
master A 172.31.1.8
www A 172.31.0.7
[root@rocky8 ~]# systemctl enable --now named
1.4.2 实现转发（只缓存）DNS服务器
[root@rocky8-2 ~]# dnf -y install bind
[root@rocky8-2 ~]# vim /etc/named.conf
options {
// listen-on port 53 { 127.0.0.1; }; #注释此行
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";
secroots-file "/var/named/data/named.secroots";
recursing-file "/var/named/data/named.recursing";
// allow-query { localhost; }; #注释此行
vim /etc/named.conf
#注释掉两行
// listen-on port 53 { 127.0.0.1; };
// allow-query { localhost; };
forward first;
forwarders { 172.31.1.8; };
#关闭dnsec功能
dnssec-enable no;
dnssec-validation no;
[root@rocky8-2 ~]# systemctl enable --now named
Created symlink /etc/systemd/system/multi-user.target.wants/named.service → /usr/lib/systemd/system/named.service.
1.4.3 web服务器配置
[root@centos7 ~]# yum -y install httpd;systemctl enable --now httpd;echo www.raymonds.cc > /var/www/html/index.html
1.4.4 在客户端测试
[root@centos7-2 ~]# vim /etc/sysconfig/network-scripts/ifcfg-eth0
DNS1=172.31.1.18
[root@centos7-2 ~]# nmcli conn reload
[root@centos7-2 ~]# nmcli conn up eth0
Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/2)
[root@centos7-2 ~]# dig www.raymonds.cc
-bash: dig: command not found
[root@centos7-2 ~]# yum -y install bind-utils
[root@centos7-2 ~]# dig www.raymonds.cc
; <<>> DiG 9.11.4-P2-RedHat-9.11.4-26.P2.el7_9.8 <<>> www.raymonds.cc
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 26263
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 13, ADDITIONAL: 27
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;www.raymonds.cc. IN A
;; ANSWER SECTION:
www.raymonds.cc. 86400 IN A 172.31.0.7
;; AUTHORITY SECTION:
. 518092 IN NS h.root-servers.net.
. 518092 IN NS k.root-servers.net.
. 518092 IN NS e.root-servers.net.
. 518092 IN NS i.root-servers.net.
. 518092 IN NS d.root-servers.net.
. 518092 IN NS b.root-servers.net.
. 518092 IN NS a.root-servers.net.
. 518092 IN NS f.root-servers.net.
. 518092 IN NS j.root-servers.net.
. 518092 IN NS c.root-servers.net.
. 518092 IN NS g.root-servers.net.
. 518092 IN NS m.root-servers.net.
. 518092 IN NS l.root-servers.net.
;; ADDITIONAL SECTION:
b.root-servers.net. 518092 IN A 199.9.14.201
a.root-servers.net. 518092 IN A 198.41.0.4
h.root-servers.net. 518092 IN A 198.97.190.53
j.root-servers.net. 518092 IN A 192.58.128.30
e.root-servers.net. 518092 IN A 192.203.230.10
d.root-servers.net. 518092 IN A 199.7.91.13
c.root-servers.net. 518092 IN A 192.33.4.12
g.root-servers.net. 518092 IN A 192.112.36.4
f.root-servers.net. 518092 IN A 192.5.5.241
i.root-servers.net. 518092 IN A 192.36.148.17
k.root-servers.net. 518092 IN A 193.0.14.129
l.root-servers.net. 518092 IN A 199.7.83.42
m.root-servers.net. 518092 IN A 202.12.27.33
b.root-servers.net. 518092 IN AAAA 2001:500:200::b
a.root-servers.net. 518092 IN AAAA 2001:503:ba3e::2:30
h.root-servers.net. 518092 IN AAAA 2001:500:1::53
j.root-servers.net. 518092 IN AAAA 2001:503:c27::2:30
e.root-servers.net. 518092 IN AAAA 2001:500:a8::e
d.root-servers.net. 518092 IN AAAA 2001:500:2d::d
c.root-servers.net. 518092 IN AAAA 2001:500:2::c
g.root-servers.net. 518092 IN AAAA 2001:500:12::d0d
f.root-servers.net. 518092 IN AAAA 2001:500:2f::f
i.root-servers.net. 518092 IN AAAA 2001:7fe::53
k.root-servers.net. 518092 IN AAAA 2001:7fd::1
l.root-servers.net. 518092 IN AAAA 2001:500:9f::42
m.root-servers.net. 518092 IN AAAA 2001:dc3::35
;; Query time: 1 msec
;; SERVER: 172.31.1.18#53(172.31.1.18) #可以看到通过10.0.0.18转发
;; WHEN: Sun Dec 05 22:04:23 CST 2021
;; MSG SIZE rcvd: 843
[root@centos7-2 ~]# curl www.raymonds.cc
www.raymonds.cc
