智能DNS

實驗目的：假設有magedu.com的網站，我們希望北京的用戶訪問時，IP是192.168.141.254 來自上海的用戶訪問時，IP是172.20.0.7,（注：此兩個IP均是centos7的僅主機與橋接），只要是客戶端的地址是192.168.141.0，就認爲是來自北京，只要是客戶端地址是172.20.0，就認爲是來自上海。
首先要搭建一個magedu.com的域，也就是搭建一個主DNS服務器。

1、[root@centos7 ~]# rpm -q bind
bind-9.9.4-72.el7.x86_64
[root@centos7 ~]# vim /etc/named.conf
options {
// listen-on port 53 { 127.0.0.1; };
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";
allow-query { localhost; };

    /* 
       recursion. 
       reduce such attack surface 
    */
    recursion yes;

    recursing-file  "/var/named/data/named.recursing";
    secroots-file   "/var/named/data/named.secroots";

// allow-query { localhost; };

    /* 
     - If you are building an AUTHORITATIVE DNS server, do NOT enable recursion.
     - If you are building a RECURSIVE (caching) DNS server, you need to enable 
       recursion.

我們把 listen-on port 53 { 127.0.0.1; };allow-query { localhost; }; 兩項給註釋掉。
2、[root@centos7 ~]# vim /etc/named.rfc1912.zones

// named.rfc1912.zones:
//
// Provided by Red Hat caching-nameserver package
//
// ISC BIND named zone configuration for zones recommended by
// RFC 1912 section 4.1 : localhost TLDs and address zones
// and http://www.ietf.org/internet-drafts/draft-ietf-dnsop-default-local-zones-02.txt
// (c)2007 R W Franks
//
// See /usr/share/doc/bind*/sample/ for example named configuration files.
//
zone "magedu.com" {
type master;
file "magedu.com.zone";
};

zone "localhost" IN {
type master;
file "named.localhost";
allow-update { none; };
};
我們把zone "magedu.com" {
type master;
file "magedu.com.zone";
} 填入。
3、[root@centos7 ~]# cd /var/named/
[root@centos7 /var/named]# ls
data named.ca named.localhost slaves
dynamic named.empty named.loopback
[root@centos7 /var/named]# vim magedu.com.zone
$TTL 1D
@ IN SOA master admin.magedu.com (1 1D 1H 1W 3H)
NS master
master A 192.168.141.254
www A 192.168.141.254
此文件是空的，我們手動寫入以上內容。
4、爲了安全起見，我們把named設置爲640.和named.ca一樣，所屬組也更改一下。
[root@centos7 /var/named]# ll
total 20
drwxrwx--- 2 named named 6 Oct 31 08:29 data
drwxrwx--- 2 named named 6 Oct 31 08:29 dynamic
-rw-r--r-- 1 root root 142 Feb 13 20:26 magedu.com.zone
-rw-r----- 1 root named 2281 May 22 2017 named.ca
-rw-r----- 1 root named 152 Dec 15 2009 named.empty
-rw-r----- 1 root named 152 Jun 21 2007 named.localhost
-rw-r----- 1 root named 168 Dec 15 2009 named.loopback
drwxrwx--- 2 named named 6 Oct 31 08:29 slaves
[root@centos7 /var/named]# chmod 640 magedu.com.zone
[root@centos7 /var/named]# chgrp named magedu.com.zone
5、啓動：[root@centos7 /var/named]# systemctl start named
[root@centos7 /var/named]#
6、我們在另一臺主機上測一下：
[root@Centos6 ~]# dig www.magedu.com @192.168.141.254

; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.68.rc1.el6 <<>> www.magedu.com @192.168.141.254
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 51906
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 1

;; QUESTION SECTION:
;www.magedu.com. IN A

;; ANSWER SECTION:
www.magedu.com. 86400 IN A 192.168.141.254

;; AUTHORITY SECTION:
magedu.com. 86400 IN NS master.magedu.com.

;; ADDITIONAL SECTION:
master.magedu.com. 86400 IN A 192.168.141.254

;; Query time: 27 msec
;; SERVER: 192.168.141.254#53(192.168.141.254)
;; WHEN: Thu Feb 7 20:11:40 2019
;; MSG SIZE rcvd: 85

以上是基本的主DNS的服務器，接下來，我們去實現智能DNS.也就是，來自不同的客戶端，去訪問主機，得到的IP是不一樣的。

首先，要實現該功能，我們要用acl區分出，訪問者是來自北京還是上海。要先定義acl：
7、使用acl命令在 options { 的上面增加三條acl，acl是客戶端的集合
[root@centos7 /var/named]# vim /etc/named.conf
// named.conf
//
// Provided by Red Hat bind package to configure the ISC BIND named(8) DNS
// server as a caching only nameserver (as a localhost DNS resolver only).
//
// See /usr/share/doc/bind*/sample/ for example named configuration files.
//
// See the BIND Administrator's Reference Manual (ARM) for details about the
// configuration located in /usr/share/doc/bind-{version}/Bv9ARM.html
acl beijingnet { 192.168.141.0/24;};
acl shanghainet { 172.20.0.0/16;};
acl othernet {any;};
options {
// listen-on port 53 { 127.0.0.1; };
listen-on-v6 port 53 { ::1; };
"/etc/named.conf" 63L, 1903C
我們要實現的目的是來自北京的客戶得到的IP與來自上海的，和來自其他城市的都不一樣。因爲此時，/etc/named.rfc1912.zones只有一套數據，所以來自各地的客戶訪問得到的結果都是一樣的，我們只有修改/etc/named.rfc1912.zones才能把訪問的數據庫給區分開來，纔會達到上述目的，這時，我們就需要用到view技術了，它就是把客戶端，也就是acl，以及與數據庫的對應關係組合起來，它的實現原理如下：
格式：
view VIEW_NAME {
match-clients { testacl; };
zone “magedu.com” {
type master;
file “magedu.com.zone”;
};
include “/etc/named.rfc1912.zones”;
};
8、[root@centos7 /var/named]# pwd
/var/named
[root@centos7 /var/named]# ls
data magedu.com.zone named.empty named.loopback
dynamic named.ca named.localhost slaves
[root@centos7 /var/named]# cp -p magedu.com.zone magedu.com.shanghai.zone
[root@centos7 /var/named]# cp -p magedu.com.zone magedu.com.beijing.zone
[root@centos7 /var/named]# ll
total 28
drwxrwx--- 2 named named 23 Feb 13 20:33 data
drwxrwx--- 2 named named 60 Feb 13 21:33 dynamic
-rw-r----- 1 root named 142 Feb 13 21:10 magedu.com.beijing.zone
-rw-r----- 1 root named 142 Feb 13 21:10 magedu.com.shanghai.zone
-rw-r----- 1 root named 142 Feb 13 21:10 magedu.com.zone
-rw-r----- 1 root named 2281 May 22 2017 named.ca
-rw-r----- 1 root named 152 Dec 15 2009 named.empty
-rw-r----- 1 root named 152 Jun 21 2007 named.localhost
-rw-r----- 1 root named 168 Dec 15 2009 named.loopback
drwxrwx--- 2 named named 6 Oct 31 08:29 slaves
此時我們看到，/var/named中只有一套數據，我們複製兩份做成上海和北京，並且修改其數據庫內容，
9、來自上海的用戶將會得到：
[root@centos7 /var/named]# vim magedu.com.shanghai.zone

$TTL 1D
@ IN SOA master admin.magedu.com ( 1 1D 1H 1W 3H )
NS master
master A 192.168.141.254
www A 172.20.0.7
來自北京的用戶將會得到：
[root@centos7 /var/named]# vim magedu.com.beijing.zone

$TTL 1D
@ IN SOA master admin.magedu.com ( 1 1D 1H 1W 3H )
NS master
master A 192.168.141.254
www A 192.168.141.254
來自其他城市的用戶將會得到：
[root@centos7 /var/named]# vim magedu.com.zone

$TTL 1D
@ IN SOA master admin.magedu.com ( 1 1D 1H 1W 3H )
NS master
master A 192.168.141.254
www A 127.0.0.7
10、[root@centos7 /var/named]# vim /etc/named.conf
// named.conf
//
// Provided by Red Hat bind package to configure the ISC BIND named(8) DNS
// server as a caching only nameserver (as a localhost DNS resolver only).
//
// See /usr/share/doc/bind*/sample/ for example named configuration files.
//
// See the BIND Administrator's Reference Manual (ARM) for details about the
// configuration located in /usr/share/doc/bind-{version}/Bv9ARM.html
acl beijingnet { 192.168.141.0/24;};
acl shanghainet { 172.20.0.0/16;};
acl othernet {any;};
options {
// listen-on port 53 { 127.0.0.1; };
listen-on-v6 port 53 { ::1; };
logging {
channel default_debug {
file "data/named.run";
severity dynamic;
};
};
view beijingview {
match-clients {beijingnet;};
include "/etc/named.rfc1912.zones.beijing";
};
view shanghaiview {
match-clients {shanghainet;};
include "/etc/named.rfc1912.zones.shanghai";
};
view otherview {
match-clients {othernet;};
include "/etc/named.rfc1912.zones";
};
include "/etc/named.root.key";

"/etc/named.conf" 68L, 2122C
我們用view做了以上操作，因爲 include "/etc/named.rfc1912.zones.beijing";
它本身就包含“magedu.com.zone”所以，在該配置文件中，用它代替。並且將 zone "." IN {
type hint;
file "named.ca"; 剪切到 /etc/named.rfc1912.zones 中，因爲當用到view技術時，該區域信息是必須放在view裏的，若放在view外邊，將來會失效。
11、我們看下面的文件，該文件要生成三個文件纔對：
[root@centos7 ~]# ll /etc/named.rfc1912.zones
-rw-r----- 1 root named 953 Feb 13 22:21 /etc/named.rfc1912.zones
[root@centos7 ~]# cp -p /etc/named.rfc1912.zones /etc/named.rfc1912.zones.beijing
[root@centos7 ~]# cp -p /etc/named.rfc1912.zones /etc/named.rfc1912.zones.shanghai
此時，我們修改北京、上海的配置文件。
[root@centos7 ~]# vim /etc/named.rfc1912.zones.beijing
zone "." IN {
type hint;
file "named.ca";
};
zone "magedu.com" {
type master;
file "magedu.com.beijing.zone";
};
"/etc/named.rfc1912.zones.beijing" 44L, 961C 18,6
在zone "magedu.com" {
type master;
file "magedu.com.zone"; 處 com. 後加上 beijing 即可。上海的同理。
[root@centos7 ~]# ll /var/named
total 28
drwxrwx--- 2 named named 23 Feb 13 20:33 data
drwxrwx--- 2 named named 60 Feb 13 21:33 dynamic
-rw-r----- 1 root named 142 Feb 13 21:45 magedu.com.beijing.zone
-rw-r----- 1 root named 138 Feb 13 21:44 magedu.com.shanghai.zone
-rw-r----- 1 root named 137 Feb 13 21:45 magedu.com.zone
-rw-r----- 1 root named 2281 May 22 2017 named.ca
-rw-r----- 1 root named 152 Dec 15 2009 named.empty
-rw-r----- 1 root named 152 Jun 21 2007 named.localhost
-rw-r----- 1 root named 168 Dec 15 2009 named.loopback
drwxrwx--- 2 named named 6 Oct 31 08:29 slaves
此時，我們可以看到三套數據庫已然生成。
root@centos7 ~]# rndc reload
server reload successful
12、此時可以看到：
[root@centos7 ~]# cat /var/named/magedu.com.beijing.zone
$TTL 1D
@ IN SOA master admin.magedu.com ( 1 1D 1H 1W 3H )
NS master
master A 192.168.141.254
www A 192.168.141.254
[root@centos7 ~]# cat /var/named/magedu.com.shanghai.zone
$TTL 1D
@ IN SOA master admin.magedu.com ( 1 1D 1H 1W 3H )
NS master
master A 192.168.141.254
www A 172.20.0.7
[root@centos7 ~]# cat /var/named/magedu.com.zone
$TTL 1D
@ IN SOA master admin.magedu.com ( 1 1D 1H 1W 3H )
NS master
master A 192.168.141.254
www A 127.0.0.7
13、我們在centos6上去dig查看：
[root@Centos6 ~]# dig www.magedu.com @192.168.141.254

; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.68.rc1.el6 <<>> www.magedu.com @192.168.141.254
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 3495
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 1

;; QUESTION SECTION:
;www.magedu.com. IN A

;; ANSWER SECTION:
www.magedu.com. 86400 IN A 192.168.141.254

;; AUTHORITY SECTION:
magedu.com. 86400 IN NS master.magedu.com.

;; ADDITIONAL SECTION:
master.magedu.com. 86400 IN A 192.168.141.254

;; Query time: 1 msec
;; SERVER: 192.168.75.254#53(192.168.141.254)
;; WHEN: Thu Feb 7 21:41:02 2019
;; MSG SIZE rcvd: 85
可以清楚的看到：www.magedu.com. 86400 IN A 192.168.141.254
[root@Centos6 network-scripts]# dig www.magedu.com @172.20.0.7

; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.68.rc1.el6 <<>> www.magedu.com @172.20.0.7
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 15235
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 1

;; QUESTION SECTION:
;www.magedu.com. IN A

;; ANSWER SECTION:
www.magedu.com. 86400 IN A 172.20.0.7

;; AUTHORITY SECTION:
magedu.com. 86400 IN NS master.magedu.com.

;; ADDITIONAL SECTION:
master.magedu.com. 86400 IN A 192.168.141.254

;; Query time: 2 msec
;; SERVER: 172.20.0.7#53(172.20.0.7)
;; WHEN: Thu Feb 7 23:01:24 2019
;; MSG SIZE rcvd: 85
可以清楚看到www.magedu.com. 86400 IN A 172.20.0.7
[root@centos7 /var/named]# dig www.magedu.com @127.0.0.1

; <<>> DiG 9.9.4-RedHat-9.9.4-72.el7 <<>> www.magedu.com @127.0.0.1
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 32872
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 2

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;www.magedu.com. IN A

;; ANSWER SECTION:
www.magedu.com. 86400 IN A 127.0.0.7

;; AUTHORITY SECTION:
magedu.com. 86400 IN NS master.magedu.com.

;; ADDITIONAL SECTION:
master.magedu.com. 86400 IN A 192.168.141.254

;; Query time: 0 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Wed Feb 13 23:01:44 CST 2019
;; MSG SIZE rcvd: 96
我們在centos7本機上dig 可以清楚看到：www.magedu.com. 86400 IN A 127.0.0.7

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