企业级dns服务器的搭建:
1.什么是dns服务：
DNS: Domain Name Service(域名解析服务)
客户端主机：
/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
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
端口 53
报错信息：
1. no servers could be reached 服务无法访问（服务开启？火墙？网络？端口？）
2. 服务启动失败 配置文件写错 journalctl -xe查询错误
3. dig 查询状态 NOERROR 表示查询成功
4. dig 查询状态 REFUSED 表示服务拒绝访问
5. dig 查询状态 RVFAIL 表示查询记录失败,（dns服务器无法到达上级，拒绝缓存）
6. dig 查询状态 NXDOMAIN 表示此域名A记录在dns中不存在
2.dns服务的安装与启用:
#安装#
dnf install bind.x86_64 -y
#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:
为了提高DNS的查询效率，并减轻根域名服务器的负荷和减少因特网上的DNS查询报文数量在域名服务器中广泛地使用了高速缓存
高速缓存用来存放最近查询过的域名以及何处获得域名映射信息的记录。
vim /etc/named.conf编辑配置文件设置高速缓存
20 forwarders {
114.114.114.114; };
systemctl restart named
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 #TIME-TO-LIVE(dns地址保存时间长度)
@ IN SOA dns.westos.com. root.westos.com ( #SOA授权起始(Start of Authority)
0 ; serial #域名版本序列号
1D ; refresh #刷新时间（辅助dns）
1H ; retry #重试时间（辅助dns）
1W ; expire #过期时间（辅助dns,查询失败过期停止对辅助域名的应答）
3H ) ; minimum #A记录最短有效期
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：
实验环境：
客户端2台
192.168.0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
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. #mail exchanger
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：
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.
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 :
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