http://raspjason.blog.51cto.com/8565009/1426561/
曾经看到很多文章把Raspberry Pi制作成无线AP，但是我今天要做的是把Raspberry Pi做成一个有NAT功能的路由器,我做这个的初衷是因为到荷兰出差后发现我的bambook无法接入宿舍里的WiFi，也许是因为宿舍无线路由器是WEP的认证方式，总之死活连不上。后来决定用Raspberry Pi+北极星光无线路由器来解决问题。
思路：
【无线路由器】-----【无线网卡--Raspberry Pi--有线RJ45端口】------【有线RJ45端口--北极星光无线路由器--无线】----Bambook
步骤一：
配置Raspberry Pi的无线网卡与有线网卡
无线网卡通过WEP连到宿舍无线路由器，并配置一个固定IP，有线网卡也配置固定IP
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pi@raspberrypi:~$ cat /etc/network/interfaces
auto lo
iface lo inet loopback
iface eth0 inet static
address 172.16.1.100
netmask 255.255.255.0
gateway 172.16.1.1
allow-hotplug wlan0
iface wlan0 inet static
wireless-essid ADSL-WiFi-c91f44
wireless-key 1234567890
address 192.168.1.100
netmask 255.255.255.0
gateway 192.168.1.254
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步骤二：
在Raspberry Pi上架设DHCP服务器
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pi@raspberrypi:~$ sudo apt-get install isc-dhcp-server
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编辑dhcp.conf文件
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pi@raspberrypi:~$ sudo vi /etc/dhcp/dhcpd.conf
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在dhcp.conf文件的最后加上以下几行
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subnet 172.16.1.0 netmask 255.255.255.0 {
range 172.16.1.1 172.16.1.99;
option routers 172.16.1.100;
option domain-name-servers 8.8.8.8,8.8.4.4;
}
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在Raspberry Pi的RJ45口上连上笔记本后测试是否可以分配IP地址
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pi@raspberrypi:~$ sudo service isc-dhcp-server restart
Stopping ISC DHCP server: dhcpd.
Starting ISC DHCP server: dhcpd.
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步骤三：
启用Raspberry Pi的路由转发功能，并开启NAT
开启路由转发功能
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pi@raspberrypi:~$ sudo vi /etc/sysctl.conf
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把sysctl.conf里的 net.ipv4.ip_forward=1前的"#"号去掉后保存
开启NAT功能
制作一个开启NAT的脚本，保存为nat
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#!/bin/sh
sudo iptables -t nat -A POSTROUTING -o wlan0 -j MASQUERADE
sudo iptables -A FORWARD -i wlan0 -o eth0 -m state --state RELATED,ESTABLISHED -j ACCEPT
sudo iptables -A FORWARD -i eth0 -o wlan0 -j ACCEPT
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运行此脚本
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pi@raspberrypi:~$ ls | grep nat
nat
pi@raspberrypi:~$ sh ./nat
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pi@raspberrypi:~$ sudo iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain FORWARD (policy ACCEPT)
target prot opt source destination
ACCEPT all -- anywhere anywhere state RELATED,ESTABLISHED
ACCEPT all -- anywhere anywhere
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
pi@raspberrypi:~$ sudo iptables -t nat -L
Chain PREROUTING (policy ACCEPT)
target prot opt source destination
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
Chain POSTROUTING (policy ACCEPT)
target prot opt source destination
MASQUERADE all -- anywhere anywhere
pi@raspberrypi:~$
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在/etc/network/目录下创建一个iptables的文件
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pi@raspberrypi:~$ sudo touch /etc/network/iptables
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把iptables内容保存到/etc/network/iptables中
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pi@raspberrypi:~$ sudo sh -c "iptables-save > /etc/network/iptables"
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pi@raspberrypi:~$ cat /etc/network/iptables
*filter
:INPUT ACCEPT [22972:1979567]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [2421:275063]
-A FORWARD -i wlan0 -o eth0 -m state --state RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -i eth0 -o wlan0 -j ACCEPT
COMMIT
*nat
:PREROUTING ACCEPT [9719:1105033]
:INPUT ACCEPT [1273:238753]
:OUTPUT ACCEPT [675:88515]
:POSTROUTING ACCEPT [219:34192]
-A POSTROUTING -o wlan0 -j MASQUERADE
COMMIT
pi@raspberrypi:~$
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在/etc/network/interfaces上加上一句up iptables-restore < /etc/network/iptables使得每次启动的时候自动生效
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pi@raspberrypi:~$ cat /etc/network/interfaces
auto lo
iface lo inet loopback
iface eth0 inet static
address 172.16.1.100
netmask 255.255.255.0
gateway 172.16.1.1
allow-hotplug wlan0
iface wlan0 inet static
wireless-essid ADSL-WiFi-c91f44
wireless-key 1234567890
address 192.168.1.100
netmask 255.255.255.0
gateway 192.168.1.254
up iptables-restore < /etc/network/iptables
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保存重启发现连上Raspberry Pi的RJ45口的便携机能自动获取IP地址，并且可以ping通外网了。
