CDN原理

BIND 视图技术实现DNS，Squid做前端缓存
简单的CDN的搭建：
1、CDN的工作原理：当外网访问内网域名的时候，外网先经过本地的dns查询，然后dns向内网搭建的dns发出申请，内网dns读取配置文件named.conf中包含IP列表的include，如果IP列表中有
该地的IP记录则对应IP列表寻找对应的视图，如没有记录则拒绝返回信息。视图将解析你访问的域名到squid缓存服务器，squid再向对应的web服务器拿取数据。
2、准备工作： 实现简单的CDN只需要4台服务器，squid，web服务器，dns，客服机。客服机、dns和squid中的一个网卡模拟外网，web和squid中的另一个网卡模拟内网。
squid：eth0:192.168.247.13 eth1:192.168.75.131
web : 192.168.75.129
dns : 192.168.247.14
xp : 192.168.247.128
3、搭建web服务： tar zxvf pcre-8.01.tar.gz
cd pcre-8.01
./configure --prefix=/usr && make && make install
tar xvf nginx-0.8.54.tar.gz -C /usr/local/src
cd /usr/local/src
./configure --prefix=/usr/local/nginx
make && make install
vim /usr/local/nginx/conf/nginx.conf
server {
listen 80 ;
server_name www.fengtao5968.com;
index index.html index.htm;
root /usr/local/www/; <--创建www文件夹，存放网页目录
error_page 404 /404.htm;
autoindex_exact_size on;
access_log /usr/local/nginx/logs/ft5968.logs combined;
}
/usr/local/nginx/sbin/nginx 启动nginx
4、搭建squid： vim /etc/security/limits.conf

• • nproc 20480
• • nofile 204800
    ulimit -SHu 20480
    ulimit -SHn 204800
    tar zxvf squid-3.0.STABLE20.tar.gz -C /usr/local/src
    cd /usr/local/src/squid-3.0.STABLE20
    ./configure --prefix=/usr/local/squid && make && make install
    vim /usr/local/squid/etc/squid.conf
    http_port 80 accel vhost vport
    cache_peer 192.168.75.129 parent 80 0 originserver name=web1
    cache_peer_domain web1 www.fengtao5968.com
    cache_mem 512 MB
    maximum_object_size_in_memory 32 KB
    cache_dir diskd /usr/local/squid/var/cache 10240 16 256 Q1=64 Q2=72
    maximum_object_size 200 MB
    logformat combined %>a %ui %un [%tl] "%rm %ru HTTP/%rv" %Hs %h" "%{User-Agent}>h" %Ss:%Sh
    access_log /usr/local/squid/var/logs/access.log combined
    cache_effective_user squid <--如果没有squid用户创建squid用户
    cache_effective_group squid
    visible_hostname sso.ft2022.com <--squid机器的主机名
    http_access allow all
    mkdir -p /usr/local/squid/var/cache
    chown squid:squid /usr/local/squid/var/cache
    mkdir -p /usr/local/squid/var/logs/
    chown squid:squid /usr/local/squid/var/logs/
    /usr/local/squid/sbin/squid -z -X <--初始化缓存目录
    /usr/local/squid/sbin/squid -D <--doman模式下启动
    测试：客服机需要在host中绑定192.168.247.13 www.fengtao5968.com
    5、搭建dns： tar zxvf bind-9.6.0.tar.gz -C /usr/local/src/
    cd /usr/local/src/bind-9.6.0/
    ./configure --prefix=/usr/local/named && make && make install
    cd /usr/local/named/
    sbin/rndc-confgen -a <--生成rndc.key
    cd etc/
    ../sbin/dnssec-keygen -a hmac-md5 -b 128 -n HOST fengtao5968 <--生成一个秘钥，提供给视图使用。该实验没有使用视图的秘钥。
    dig > named.ca
    vim named.conf
    options {
    directory "/usr/local/named/etc"; <--要写named安装路径下的named.conf
    allow-query-cache {any;};
    pid-file "named.pid";
    include "rndc.key";
    controls {
    inet 127.0.0.1 allow { localhost; } keys { rndc-key; };
    };
    logging {
    channel query_log {
    file "query.log" versions 3 size 20m;
    severity info;
    print-time yes;
    print-category yes;
    };
    category queries {
    query_log;
    };
    };
    include "ip.fengtao5968"; vim /usr/local/named/etc/ip.fengtao5968
    view "view_fengtao5968" { acl "FENGTAO5968" {
    match-clients { FENGTAO5968; }; 192.168.24.0/24;
    recursion yes; 192.168.247.0/24;<-- 一定要包含本机的网段，否则dns无法解析到视图。
    zone "." IN { };
    type hint;
    file "named.ca";
    };
    zone "localhost" IN { vim /usr/local/named/etc/localhost.zone
    type master; ORIGIN localhost.
    allow-update { none; }; @ 1D IN SOA @ root (
    }; 42 ; serial (d. adams)
    zone "0.0.127.in-addr.arpa" IN { 3H;
    type master; 15M;
    file "named.local"; 1W;
    allow-update { none; }; 1D )
    }; 1D IN NS @
    zone "fengtao5968.com" IN{ 1D IN A 127.0.0.1
    type master;
    file "fengtao5968.conf";
    allow-update { none; };
    };
    };
    vim /usr/local/named/etc/named.local
    TTL 180
    $ORIGIN fengtao5968.com.
    @ IN SOA @ root. ( 实验中不要用域名替代第二个@，否则会出现找不到相应域名的错误日志。
    2013040610
    180
    900
    3600000
    3600 )
    NS @
    www CNAME ftp.fengtao5968.com.
    ftp.fengtao5968.com. IN A 192.168.247.13
    测试：/usr/local/named/sbin/named-checkconf /usr/local/named/etc/named.conf
    启动：/usr/local/named/sbin/named
    查看系统日志：tail -f /var/log/messages 若无错误实验基本上成功
    检测域名是否可用：dig www.fengtao5968.com 若被检测到squid的IP上去就表示成功
    6、测试： 将客服机的dns指向dns服务器即可。