实验环境：
系统 centos6.3
内网 eth0：192.168.223.163
外网 eth1：192.168.22.78 Squid Cache: Version squid-3.1.10网卡配置如下：
内网：
外网：
安装
[root ~]# yum -y install squid
Installing : 7:squid-3.1.10-18.el6_4.x86_64
Verifying : 7:squid-3.1.10-18.el6_4.x86_64
Installed:
squid.x86_64 7:3.1.10-18.el6_4
Complete!
配置文件如下（更改地方用红色）
[root ~]# vim /etc/squid/squid.conf
#
# Recommended minimum configuration:
#
acl manager proto cache_object
acl localhost src 127.0.0.1/32 ::1
acl to_localhost dst 127.0.0.0/8 0.0.0.0/32 ::1
# Example rule allowing access from your local networks.
# Adapt to list your (internal) IP networks from where browsing
# should be allowed
acl localnet src 10.0.0.0/8 # RFC1918 possible internal network
acl localnet src 172.16.0.0/12 # RFC1918 possible internal network
acl localnet src 192.168.0.0/16 # RFC1918 possible internal network
acl localnet src fc00::/7 # RFC 4193 local private network range
acl localnet src fe80::/10 # RFC 4291 link-local (directly plugged) machines
acl SSL_ports port 443
acl Safe_ports port 80 # http
acl Safe_ports port 21 # ftp
acl Safe_ports port 443 # https
acl Safe_ports port 70 # gopher
acl Safe_ports port 210 # wais
acl Safe_ports port 1025-65535 # unregistered ports
acl Safe_ports port 280 # http-mgmt
acl Safe_ports port 488 # gss-http
acl Safe_ports port 591 # filemaker
acl Safe_ports port 777 # multiling http
acl CONNECT method CONNECT
#acl worktime time 8:00-23:59 //定义工作时间
#acl worktime time 00:00-5:59
#http_access allow mynetwork !worktime //只允许非工作时间上网
#
# Recommended minimum Access Permission configuration:
#
# Only allow cachemgr access from localhost
http_access allow manager localhost
http_access deny manager
# Deny requests to certain unsafe ports
http_access deny !Safe_ports
# Deny CONNECT to other than secure SSL ports
http_access deny CONNECT !SSL_ports
# We strongly recommend the following be uncommented to protect innocent
# web applications running on the proxy server who think the only
# one who can access services on "localhost" is a local user
#http_access deny to_localhost
#
# INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS
#
# Example rule allowing access from your local networks.
# Adapt localnet in the ACL section to list your (internal) IP networks
# from where browsing should be allowed
http_access allow localnet
http_access allow localhost
# And finally deny all other access to this proxy
http_access allow all
# Squid normally listens to port 3128
http_port 192.168.223.163:3128 transparent
# We recommend you to use at least the following line.
hierarchy_stoplist cgi-bin ?
# Uncomment and adjust the following to add a disk cache directory.
cache_dir ufs /var/spool/squid 2000 16 256
# Leave coredumps in the first cache dir
coredump_dir /var/spool/squid
# Add any of your own refresh_pattern entries above these.
refresh_pattern ^ftp: 1440 20% 10080
refresh_pattern ^gopher: 1440 0% 1440
refresh_pattern -i (/cgi-bin/|\?) 0 0% 0
refresh_pattern . 0 20% 4320
visible_hostname 192.168.223.163
cache_mem 256 MB //squid服务器占用内存大小
forwarded_for off //不传递被代理地址
via off //不传递代理服务器信息
初始化squid代理服务器
[root ~]# squid -z
2013/08/14 10:06:24| Creating Swap Directories
2013/08/14 10:06:24| /var/spool/squid exists
2013/08/14 10:06:24| Making directories in /var/spool/squid/00
2013/08/14 10:06:24| Making directories in /var/spool/squid/01
2013/08/14 10:06:24| Making directories in /var/spool/squid/02
2013/08/14 10:06:24| Making directories in /var/spool/squid/03
2013/08/14 10:06:24| Making directories in /var/spool/squid/04
2013/08/14 10:06:24| Making directories in /var/spool/squid/05
2013/08/14 10:06:24| Making directories in /var/spool/squid/06
2013/08/14 10:06:24| Making directories in /var/spool/squid/07
2013/08/14 10:06:24| Making directories in /var/spool/squid/08
2013/08/14 10:06:24| Making directories in /var/spool/squid/09
2013/08/14 10:06:24| Making directories in /var/spool/squid/0A
2013/08/14 10:06:24| Making directories in /var/spool/squid/0B
2013/08/14 10:06:24| Making directories in /var/spool/squid/0C
2013/08/14 10:06:24| Making directories in /var/spool/squid/0D
2013/08/14 10:06:24| Making directories in /var/spool/squid/0E
2013/08/14 10:06:24| Making directories in /var/spool/squid/0F
开启路由功能，并将下面的命令写入/etc/rc.d/rc.local 文件，使其开机自动开启路由功能
[root ~]# echo '1'>/proc/sys/net/ipv4/ip_forward
或者如下 vi /etc/sysctl.conf文件 将 net.ipv4.ip_forward = 0 改成 =1
[root ~]# sysctl -p
net.ipv4.ip_forward = 1
配置iptables防火墙
自动将http请求转发到代理服务器上
[root@only ~]# iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT --to-ports 3128
设置源地址映射
[root@only ~]# iptables -t nat -A POSTROUTING -j SNAT --to-source 192.168.22.78
[root@only ~]# iptables -P INPUT ACCEPT
启动squid代理服务
[root@only ~]# service squid restart
Stopping squid: [FAILED]
Starting squid: . [ OK ]
查看squid代理服务器缓存日志
[root@only ~]# tail -f /var/log/squid/access.log
将squid加入开机启动项
[root@only ~]# chkconfig squid --level 235 on
搞定。