Application of Linux as Proxy server in simple way

Now use Linux as a proxy service is more and more, I am a piece of cake on this aspect is not know to find someone to learn. However, a person with money mainly, originally money also does not matter as long as can learn something, ability can learn to hand also line.
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But some people are too black, unexpectedly want me to 1000+RMB, I a small network management that come so much money, can only grope for oneself. Found on the internet for more than a tutorial, do not succeed, can be a little brother too stupid can not understand the words of the master door did not do a good job, and found some information about iptables in the net, finally I was out.

Now I'm going to write my practice and share it with you. May be the simplest way, we do not laugh brother Oh. If the master looked, please give a lot of advice. Crap less, now get to the point.

Linux as the simplest way to do proxy server, using RedHat9.0 as an example

Find a machine that can install Linux at least two network adapters

1. Install Linux, whether in graphics, or style can be, choose the smallest installation, in the installation can configure the IP and DNS (not set also line), all other default

When installed, enter the prompt

2. After entering the prompt, configure the following network card first:

Eth0 (External network adapter) configuration file The path is:/etc/sysconfig/network-scripts/ifcfg-eth0

Use Vi/etc/sysconfig/network-scripts/ifcfg-eth0 to modify the content of eth0, if installed when the match is not to be matched, check the wrong without the line.

Eth0 content is: (note IP for hypothetical IP, #为注释不用写)

Device=eth0 #11585. html "> Hardware Device name

Bootproto=static #配置方式

broadcast=218.28.9.255 #广播地址

Ipaddr=218.28.9.123 #是你的IP地址

netmask=255.255.255.0 #子网掩码

network=218.28.9.0 #整个网段的地址

Onboot=yes #是否启用网卡 (generally default is open)

Eth1 (intranet network card), configuration file path is:/etc/sysconfig/network-scripts/ifcfg-eth1

Modify the contents of eth0 with Vi/etc/sysconfig/network-scripts/ifcfg-eth1

The contents of eth1 are:

Device=eth1 #硬件设备名

Bootproto=static #配置方式

broadcast=192.168.0.255 #广播地址

ipaddr=192.168.0.1 #是你的IP地址

netmask=255.255.255.0 #子网掩码

network=192.168.0.0 #整个网段的地址

Onboot=yes #是否启用网卡 (generally default is open)

The NIC is configured, you can use Ifconfig to check the network card with the wrong