dns服务器部署

1.关于dns的名词解释

【1】dns:
domain name service(域名解析服务)
将域名解析成ip
【2】关于客户端:

/etc/resolv.conf	dns指向文件
host www.baidu.com	地址解析命令
dig www.baidu.com	地址详细解析信息命令
A记录	ip地址叫做域名的Address 记录
SOA	授权起始主机
dns顶级	. 13
次级	.com .net .edu .org …

/etc/resolv.conf ##dns指向文件
host www.baidu.com ##地址解析命令
dig www.baidu.com ##地址详细解析信息命令

NOERROR表示地址解析成功了
QUESTION SECTION  表示我们的问题，问百度是谁
ANSWER SECTION 表示的是我们的答案，可以看到百度的域名被我们内部转换为ip
Query time  查看的时间
SERVER 服务器，询问了114.114.114.114的53端口

A记录 ##ip地址叫做域名的Address 记录
baidu转为了内部域名，之后转换为了ip，ip。。。。。。
SOA ##授权起始主机

DNS解析方式：逐级

dns顶级
. 13
次级
.com .net .edu .org …
baidu.com

【3】关于服务端

bind	安装包
named	服务名称
/etc/named.conf	主配置文件
/var/named	数据目录
53	端口

【4】关于报错信息：

报错	错误内容
no servers could be reached	服务无法访问（服务开启？火墙？网络？端口？）
服务启动失败	配置文件写错 journalctl -xe查询错误

dig 查询状态

NOERROR	表示查询成功
REFUSED	服务拒绝访问
SERVFAIL	查询记录失败,（dns服务器无法到达上级，拒绝缓存）
NXDOMAIN	此域名A记录在dns中不存在

2.dns服务的安装与启用

【1】安装
dnf install bind.x86_64 -y

【2】启用

systemctl enable --now named
firewall-cmd --permanent --add-service=dns + firewall-cmd --reload
vim /etc/named.conf

11 listen-on port 53 { any; }; ##在本地所有网络接口上开启53端口
19 allow-query { any; }; ##允许查询A记录的客户端列表
34 dnssec-validation no; ##禁用dns检测使dns能够缓存外部信息到本纪

systemctl restart named

3.高速缓存dns

20 forwarders { 114.114.114.114; };

4.dns的正向解析

vim /etc/named.rfc1912.zone

zone "westos.com" IN { ##维护的域名
 type master; ##当前服务器位主dns
 file "westos.com.zone"; ##域名A记录文件
 allow-update { none; }; ##允许更新主机列表
};

cd /var/named/
cp -p named.localhost westos.com.zone

$TTL 1D
@ IN SOA dns.westos.com. root.westos.com (
 0 ; serial
 1D ; refresh
 1H ; retry
 1W ; expire
 3H ) ; minimum
 NS dns.westos.com.
dns A 192.168.0.20
www CNAME westos.a.westos.com. ##规范域名
westos.a A 192.168.0.111 ##正向解析记录
westos.a A 192.168.0.112
westos.com. MX 1 192.168.0.20. ##邮件解析记录

systemctl restart named
dig www.westos.com #查询正向解析
dig -t mx westos.com #邮件解析记录查询

5.dns的反向解析

vim /etc/named.rfc1912.zones

zone "0.168.192.in-addr.arpa" IN {
type master;
file "192.168.0.ptr";
allow-update { none; };
};

cd /var/named/
cp -p named.loopback 192.168.0.ptr
vim 192.168.0.ptr

$TTL 1D
@ IN SOA dns.westos.com. root.westos.com. (
0 ; serial
1D ; refresh
1H ; retry
1W ; expire
3H ) ; minimum
NS dns.westos.com.
dns A 192.168.0.20
11 PTR www.westos.com.
12 PTR bbs.westos.com.
13 PTR news.westos.com.

systemctl restart named

测试：
dig -x 192.168.0.11

6.dns的双向解析

【1】实验环境：

客户端2台
192.168.1网段
172.25.254网段 ##ifconfig ens160 172.25.254.30 netmask 255.255.255.0
服务端1台2个网段的ip
192.168.0.20
172.25.254.20 ##ifconfig ens160 172.25.254.20 netmask 255.255.255.0
在192.168.0网段的客户主机中
vim /etc/resolv.conf
nameserver 192.168.0.20
在172.25.254网段的客户主机中
vim /etc/resolv.conf
nameserver 172.25.254.20

【2】配置方式：

cd /var/named/
cp -p westos.com.zone westos.com.inter
vim westos.com.inter

$TTL 1D
@ IN SOA dns.westos.com. root.westos.com (
0 ; serial
1D ; refresh
1H ; retry
1W ; expire
3H ) ; minimum
NS dns.westos.com.
dns A 172.25.254.20
www CNAME westos.a.westos.com.
westos.a A 172.25.254.111
westos.a A 172.25.254.112
westos.com. MX 1 172.25.254.20.

cp -p /etc/named.rfc1912.zones /etc/named.rfc1912.inters
vim /etc/named.rfc1912.inters

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

vim /etc/named.conf

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

view localnet {
 match-clients { 192.168.0.0/24; };
 zone "." IN {
 type hint;
 file "named.ca";
 };
 include "/etc/named.rfc1912.zones";
 include "/etc/named.root.key";
};

view internet {
 match-clients { any; };
 zone "." IN {
 type hint;
 file "named.ca";
 };
 include "/etc/named.rfc1912.inters";
 include "/etc/named.root.key";
};

systemctl restart named

测试：分别在2个网段的主机中作同样域名的地址解析
得到的A记录不同

7.dns集群

【1】主dns：

zone "westos.com" IN {
 type master;
 file "westos.com.zone";
 allow-update { none; };
 also-notify { 192.168.0.30; }; ##主动通知的辅助dns主机
};

vim /var/named/westos.com.zone

$TTL 1D
@ IN SOA dns.westos.com. root.westos.com (
 2020031402 ; serial ##每次修改A记录文
件需要
 1D ; refresh ##变更此参数的值
 1H ; retry
 1W ; expire
 3H ) ; minimum
 NS dns.westos.com.
dns A 192.168.0.20
www CNAME westos.a.westos.com.
westos.a A 192.168.0.210
westos.a A 192.168.0.211
westos.com. MX 1 192.168.0.20.

【2】slave dns：

dnf install bind -y
firewall-cmd --add-service=dns
vim /etc/named.conf

listen-on port 53 { any; };
allow-query { any; };
dnssec-validation no;

vim /etc/named.rfc1912.zone

zone "westos.com" IN {
 type slave; ##dns状态位辅助dns
 masters { 192.168.0.20; }; ##主dns
 file "slaves/westos.com.zone"; ##同步数据文件
};

systemctl restart named

8.dns的更新

【1】dns基于ip地址的更新：
在dns中设定：

vim /etc/named.rfc1912.zones

zone "westos.com" IN {
 type master;
 file "westos.com.zone";
 allow-update { 192.168.0.10; }; ##允许指定客户端更新westos域
 also-notify { 192.168.0.30; };
};

测试：
在192.168.0.10
[root@rhel7_node1 ~]# nsupdate

server 192.168.0.20
update add hello.westos.com 86400 A 192.168.0.111 ##新曾A记录
send
update delete hello.westos.com ##删除A记录
send
dns基于key更新的方式:
dnssec-keygen -a HMAC-SHA256 -b 128 -n HOST westos
cp -p /etc/rndc.key /etc/wesots.key
vim /etc/wesots.key
key “westos” {
algorithm hmac-sha256;
secret “SB1tQcLaWeroU9lGW21zeA==”;
};
vim /etc/named.conf
43 include “/etc/wesots.key”;
vim /etc/named.rfc1912.zones
zone “westos.com” IN {
type master;
file “westos.com.zone”;
allow-update { key westos; };
also-notify { 192.168.0.30; };
};
systemctl restart named
[root@rhel7_node1 ~]# nsupdate -k /mnt/Kwestos.+163+26695.private
server 192.168.0.20
update add hello.westos.com 86400 A 192.168.0.111
send
quit

9.ddns（dhcp+dns）

dnf instsall dhcp-server -y
vim /etc/dhcpd/dhcpd.conf

# dhcpd.conf
#
# Sample configuration file for ISC dhcpd
#
# option definitions common to all supported networks...
option domain-name "westos.com";
option domain-name-servers 192.168.0.20;
default-lease-time 600;
max-lease-time 7200;
# Use this to enble / disable dynamic dns updates globally.
ddns-update-style interim;
# If this DHCP server is the official DHCP server for the local
# network, the authoritative directive should be uncommented.
#authoritative;
# Use this to send dhcp log messages to a different log file (you also
# have to hack syslog.conf to complete the redirection).
log-facility local7;
# No service will be given on this subnet, but declaring it helps the 
# DHCP server to understand the network topology.
# This is a very basic subnet declaration.


subnet 192.168.0.0 netmask 255.255.255.0 {
 range 192.168.0.51 192.168.0.80;
 option routers 192.168.0.1; }
key westos {
 algorithm hmac-sha256;
 secret SB1tQcLaWeroU9lGW21zeA==;
 };
zone westos.com. {
primary 127.0.0.1;
key westos;
}

dns的key更新
测试：设定测试主机网络工作方式为dhcp
设定主机名称test.westos.com
重启网络
dig test.westos.com
可以得到正确解析

ly_qiu

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