RHEL7 DNS 服务 unbound 测试

Posted 遠離塵世の方舟

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测试环境:

rhel1.rusky.com 192.168.100.1 RHEL7(辅DNS)
rhel2.rusky.com 192.168.100.2 RHEL7(主DNS)
rhdl3.rusky.com 192.168.100.3 RHEL6

一、搭建主DNS服务器

在安装前先停止系统自带的dnsmasq服务,因为该服务也用53端口,并且已经启动。否则 unbound服务无法启动。

[[email protected] ~]# netstat -antulp | grep 53
tcp        0      0 192.168.122.1:53        0.0.0.0:*               LISTEN      1403/dnsmasq        
udp        0      0 192.168.122.1:53        0.0.0.0:*                           1403/dnsmasq        
udp        0      0 0.0.0.0:5353            0.0.0.0:*                           678/avahi-daemon: r 
[[email protected] ~]# ps -ef | grep dnsmasq
nobody    1403     1  0 16:12 ?        00:00:00 /usr/sbin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/default.conf --leasefile-ro --dhcp-script=/usr/libexec/libvirt_leaseshelper
root      1404  1403  0 16:12 ?        00:00:00 /usr/sbin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/default.conf --leasefile-ro --dhcp-script=/usr/libexec/libvirt_leaseshelper
root      2210  1642  0 16:32 pts/0    00:00:00 grep --color=auto dnsmasq
[[email protected] ~]# kill -9 1403

然后执行#systemctl disable dnsmasq禁止开机启动。

1、安装 unbound服务

#yum install unbound -y

# netstat -antulp | grep unbound   --查看监听端口53
tcp 0 0 127.0.0.1:53 0.0.0.0:* LISTEN 10478/unbound 
tcp 0 0 127.0.0.1:8953 0.0.0.0:* LISTEN 10478/unbound 
tcp6 0 0 ::1:53 :::* LISTEN 10478/unbound 
tcp6 0 0 ::1:8953 :::* LISTEN 10478/unbound 
udp 0 0 0.0.0.0:28416 0.0.0.0:* 10478/unbound 
udp 0 0 127.0.0.1:53 0.0.0.0:* 10478/unbound 
udp6 0 0 ::1:53 :::* 10478/unbound

2、修改主配置文件

# vi /etc/unbound/unbound.conf 
interface: 0.0.0.0
access-control: 0.0.0.0/0 allow
username: ""

3、重启unbound服务

# systemctl restart unbound
# netstat -antulp | grep unbound
tcp 0 0 0.0.0.0:53 0.0.0.0:* LISTEN 11234/unbound 
tcp 0 0 127.0.0.1:8953 0.0.0.0:* LISTEN 11234/unbound 
tcp6 0 0 ::1:8953 :::* LISTEN 11234/unbound 
udp 0 0 0.0.0.0:16314 0.0.0.0:* 11234/unbound 
udp 0 0 0.0.0.0:53 0.0.0.0:* 11234/unbound

4、新增配置文件

# vi /etc/unbound/local.d/rusky.com.conf
local-zone:"rusky.com." static
local-data:"rusky.com. 86400 IN SOA ns.rusky.com. root.rusk.com. 120000 86400 3600 10800 86400"
local-data:"rusky.com. IN NS ns.rusky.com."
local-data:"rusky.com. IN MX 10 mail.rusky.com."
local-data:"rusky.com. IN MX 20 smtp.rusky.com."
local-data:"rusky.com. IN A 192.168.100.2"
local-data:"ns.rusky.com. IN A 192.168.100.2"
local-data:"mail.rusky.com. IN A 192.168.100.2"
local-data:"smtp.rusky.com. IN A 192.168.100.2"
local-data:"ftp.rusky.com. IN A 192.168.100.2"
local-data:"www.rusky.com. IN A 192.168.100.2"
local-data:"rhel1.rusky.com. IN A 192.168.100.1"
local-data:"rhel2.rusky.com. IN A 192.168.100.2"
local-data:"rhel3.rusky.com. IN A 192.168.100.3"

#lookback反向解析
local-data-ptr:"192.168.100.2 ns.rusky.com."
local-data-ptr:"192.168.100.2 mail.rusky.com."
local-data-ptr:"192.168.100.2 smtp.rusky.com."
local-data-ptr:"192.168.100.2 ftp.ns.rusky.com."
local-data-ptr:"192.168.100.2 www.ns.rusky.com."
local-data-ptr:"192.168.100.1 rhel1.rusky.com."
local-data-ptr:"192.168.100.2 rhel2.rusky.com."
local-data-ptr:"192.168.100.3 rhel3.rusky.com."

正向解析的时候还可以这样:

local-data:"www.rusky.com. IN A 192.168.100.2"
local-data:"www.rusky.com. IN A 192.168.100.3"
local-data:"www.rusky.com. IN A 192.168.100.4"
local-data:"www.rusky.com. IN A 192.168.100.5"

一个域名指向多个主机IP,这样每次解析都会指向不同的主机,实现一个简单的负载均衡功能。

========================================================
说明:

local-zone:"rusky.com." static  //定义一个域
local-data:"rusky.com. 86400 IN SOA ns.rusky.com. root.rusk.com. 120000 86400 3600 10800 86400"   //主辅DNS服务器进行数据同步的控制参数
86400  //TTL资源记录的生存时间。
IN   //表示标准DNS的internet类。
SOA   //起始授权(Start Of Authority)记录,每个区域都有一条SOA记录,用于指定本区域内负责解析的DNS服务器中哪个是主授权服务器,以及管理区域的负责人的邮箱地址和主、辅授权DNS服务器之间实现数据同步的控制参数。
ns.rusky.com.   //定义域内主DNS服务器。ns.rusky.com不是主机名,ns表示所有的域名,比如mail.rusky.com,www.rusky.com,bbs.rusky.com等。
root.rusk.com.   //邮箱地址,不需要带@符号
120000   //每次修改区域记录时,都会增加序列号的值,它是辅授权DNS服务器更新数据的依据。
辅助DNS服务器跟主DNS服务器同步时才用到。当master服务器DNS信息有变化时,该值加1,而辅助DNS服务器检查到该值有变化时,就会进行数据同步。这个数不是固定的。生产尽量设置6位数以上。
86400   //(1天) 刷新时间。每隔一天跟主DNS服务器同步一次数据。
辅授权DNS服务器根据此时间间隔周期性地检查主授权DNS服务器的序列号是否改变,若有改变则更新自己的区域记录(以秒为单位)
3600  //(1小时)重试延时。如果前一次同步失败,则隔1小时候再去同步。
10800   //(3小时) 如果同步三次都失败,则不再同步。
86400   //DNS缓存时间。因为前边几次都同步失败了,所以86400秒后,辅助DNS服务器将失效。
MX 10
MX 20   //这两行是优先级别,值越小,优先级越高。
(邮件交换(Mail Exchange)记录,用于将属于该区域的邮件域(即邮箱地址@后面的字符串)映射到邮件服务器的域名。

重启unbound服务。

# systemctl restart unbound

5、修改网卡DNS配置指向rhel2

修改三台服务器的DNS都指向192.168.100.2

6、测试DNS解析

[[email protected] ~]# ping rhel2.rusky.com -c 2
PING rhel2.rusky.com (192.168.100.2) 56(84) bytes of data.
64 bytes from www.ns.rusky.com (192.168.100.2): icmp_seq=1 ttl=64 time=0.193 ms
64 bytes from www.ns.rusky.com (192.168.100.2): icmp_seq=2 ttl=64 time=0.350 ms

--- rhel2.rusky.com ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 0.193/0.271/0.350/0.080 ms
[[email protected] ~]# ping www.rusky.com -c 2
PING www.rusky.com (192.168.100.2) 56(84) bytes of data.
64 bytes from ftp.ns.rusky.com (192.168.100.2): icmp_seq=1 ttl=64 time=0.278 ms
64 bytes from ftp.ns.rusky.com (192.168.100.2): icmp_seq=2 ttl=64 time=0.357 ms

--- www.rusky.com ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1002ms
rtt min/avg/max/mdev = 0.278/0.317/0.357/0.043 ms
[[email protected] ~]# nslookup
> mail.rusky.com
Server:         192.168.100.2
Address:        192.168.100.2#53

Name:   mail.rusky.com
Address: 192.168.100.2
> 192.168.100.3
Server:         192.168.100.2
Address:        192.168.100.2#53

3.100.168.192.in-addr.arpa      name = rhel3.rusky.com.
> rhel2.rusky.com
Server:         192.168.100.2
Address:        192.168.100.2#53

Name:   rhel2.rusky.com
Address: 192.168.100.2
> 192.168.100.1
Server:         192.168.100.2
Address:        192.168.100.2#53

1.100.168.192.in-addr.arpa      name = rhel1.rusky.com.
> 

二、搭建辅DNS服务器

同上,先停止并禁用dnsmasq服务,再安装unbound服务,然后修改主配置文件的三个参数。

#yum install unbound -y

# vi /etc/unbound/unbound.conf
interface: 0.0.0.0
access-control: 0.0.0.0/0 allow
username: "“

然后新增配置文件rusky.com.conf,修改内容如下:

# vi /etc/unbound/local.d/rusky.com.conf

[[email protected] ~]# cat /etc/unbound/local.d/rusky.com.conf 
domain-insecure:"rusky.com."
forward-zone:
        name:"."
        forward-addr:"192.168.100.2"

说明:

当客户机到192.168.100.1来请求DNS解析时,则转发到192.168.100.2服务器进行解析,如果解析成功,则缓存一份到本地。以后其它机器再到192.168.100.2来请求DNS解析时,则不需要转发了,直接使用本地缓存的数据。
再加上一句:
domain-insecure:"rusky.com"
表示不需要进行安全检测。

同时,主DNS 192.168.100.2 服务器上的该配置文件里也需要加上这行参数。
然后都重启unbound服务。

测试:

rtt min/avg/max/mdev = 0.196/0.196/0.196/0.000 ms
[[email protected] ~]# hostname
rhel3.rusky.com
[[email protected] ~]# cat /etc/resolv.conf 
# Generated by NetworkManager
search rusky.com
nameserver 192.168.100.1
[[email protected] ~]# ping rhel1.rusky.com
PING rhel1.rusky.com (192.168.100.1) 56(84) bytes of data.
64 bytes from 192.168.100.1: icmp_seq=1 ttl=64 time=0.275 ms
^C
--- rhel1.rusky.com ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 713ms
rtt min/avg/max/mdev = 0.275/0.275/0.275/0.000 ms
[[email protected] ~]# ping www.rusky.com -c 2
PING www.rusky.com (192.168.100.2) 56(84) bytes of data.
64 bytes from 192.168.100.2: icmp_seq=1 ttl=64 time=1.22 ms
64 bytes from 192.168.100.2: icmp_seq=2 ttl=64 time=0.677 ms

--- www.rusky.com ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1003ms
rtt min/avg/max/mdev = 0.677/0.949/1.221/0.272 ms
[[email protected] ~]# nslookup
> rhel1.rusky.com
Server:         192.168.100.1
Address:        192.168.100.1#53

Non-authoritative answer:
Name:   rhel1.rusky.com
Address: 192.168.100.1
> 

停止rhel2上的unbound服务后,再到rhel3来测试DNS解析:

[[email protected] ~]# nslookup
> mail.rusky.com
Server:         192.168.100.1
Address:        192.168.100.1#53

** server cant find mail.rusky.com.rusky.com: SERVFAIL
> rhel2.rusky.com
;; connection timed out; trying next origin
Server:         192.168.100.1
Address:        192.168.100.1#53

** server cant find rhel2.rusky.com.rusky.com: SERVFAIL
> www.rusky.com
Server:         192.168.100.1
Address:        192.168.100.1#53

Non-authoritative answer:
Name:   www.rusky.com
Address: 192.168.100.2
> 

说明,当主DNS服务rhel2停止后,从rhel3服务器到rhel1进行DNS解析时,只能解析已缓存到本地的记录。而之前未解析过的,也就是未缓存到rhel1的,则解析失败。

 






















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