Setup Raspberry Pi as Wireless Router

入手Raspberry Pi Model B (512MB) 已经一段时间了。装上官方的Raspbian，感觉跟手头上的AO522没区别。同样是基于Debian，同样是LXDE桌面。也试了下Xbian (XMBC + Raspbian)，感觉非常棒，只是菜单操作有点卡。可惜手上的SD卡空间不够大，否则，还可以玩玩Android。

玩过后，正是按计划进行。首先是作为无线路由来使用。其实就跟Lubuntu共享WiFi一样，测试过程中，还改良了一下以前写的sharewifi脚本（以前的版本：http://www.foxail.org/blog/?p=490）。但是还有一个问题，执行该脚本的stop操作后，系统不会把建立的mon.wlan0接口关闭，需要重启系统，wifi才能从共享模式变成正常的接收模式。

1）sharewifi脚本，设置共享wifi，我放在/opt下，内容如下：（首先要安装hostapd和dnsmasq，执行sudo apt-get install hostapd dnsmasq即可）

### begin the file /opt/sharewifi #########################################
#!/bin/sh

# Setup wireless AP, share the Internet from interface0 to interface1
# USAGE: sharewifi [ start | stop ] interface0 interface1
# EXAMPLE: sharewifi start wlan1 wlan0

help( )
{
    cat << HELP
    Setup wireless AP, share the Internet from interface0 to interface1
    USAGE: sharewifi [ help | start | stop ] interface0 interface1
    EXAMPLE: sharewifi start wlan1 wlan0

    List clients:
    cat /var/lib/misc/dnsmasq.leases
    HELP
    exit 0
}

start( )
{
    echo Starting share wifi ......
    echo Share Internet $port_in to $port_out

    # Configure iptable rules
    iptables -F
    iptables -t nat -A POSTROUTING -s $ip_prefix.0/24 -o $port_in -j MASQUERADE
    iptables -A FORWARD -s $ip_prefix.0/24 -o $port_in -j ACCEPT
    iptables -A FORWARD -d $ip_prefix.0/24 -m conntrack --ctstate ESTABLISHED,RELATED -i $port_in -j ACCEPT

    # Log the message of route
    #iptables -A INPUT -m conntrack --ctstate NEW -p tcp --dport 80 -j LOG --log-prefix "NEW_HTTP_CONN: "

    # Save iptable rules
    sh -c "iptables-save > /etc/iptables.rules"

    # Configure hostapd
    hostapd_conf=/etc/hostapd/hostapd.conf
    [ -f $hostapd_conf ] && rm $hostapd_conf
    echo >> $hostapd_conf interface=$port_out
    echo >> $hostapd_conf driver=nl80211
    echo >> $hostapd_conf ssid=foxrpi-ap
    echo >> $hostapd_conf channel=1
    echo >> $hostapd_conf hw_mode=g
    echo >> $hostapd_conf auth_algs=1
    echo >> $hostapd_conf wpa=3
    echo >> $hostapd_conf wpa_passphrase=1234567890
    echo >> $hostapd_conf wpa_key_mgmt=WPA-PSK
    echo >> $hostapd_conf wpa_pairwise=TKIP CCMP
    echo >> $hostapd_conf rsn_pairwise=CCMP
    chmod 755 $hostapd_conf

    # Configure /etc/dnsmasq.conf
    dnsmasq_conf=/etc/dnsmasq.conf
    [ -f $dnsmasq_conf ] && rm $dnsmasq_conf
    echo >> $dnsmasq_conf interface=$port_out
    echo >> $dnsmasq_conf bind-interfaces #这个是只监听wlan0，没有之会检测所有卡
    echo >> $dnsmasq_conf except-interface=lo
    echo >> $dnsmasq_conf dhcp-range=$ip_prefix.10,$ip_prefix.110,6h #设置dhcp地址范
    chmod 755 $dnsmasq_conf

    # Enable routing
    sysctl net.ipv4.ip_forward=1

    #killall named
    /etc/init.d/hostapd stop
    ifconfig $port_out $ip_prefix.1
    hostapd -B $hostapd_conf
    /etc/init.d/dnsmasq restart

    echo Sucess share wifi

    exit 0
}

stop( )
{
    echo Stopping share wifi ......
    echo Stop share Internet $port_in to $port_out

    # Configure iptable rules
    iptables -F

    # Log the message of route
    #iptables -A INPUT -m conntrack --ctstate NEW -p tcp --dport 80 -j LOG --log-prefix "NEW_HTTP_CONN: "

    # Save iptable rules
    sh -c "iptables-save > /etc/iptables.rules"

    # Configure hostapd
    hostapd_conf=/etc/hostapd/hostapd.conf
    [ -f $hostapd_conf ] && rm $hostapd_conf

    # Configure /etc/dnsmasq.conf
    dnsmasq_conf=/etc/dnsmasq.conf
    [ -f $dnsmasq_conf ] && rm $dnsmasq_conf

    # Enable routing
    sysctl net.ipv4.ip_forward=0

    #killall named
    /etc/init.d/hostapd stop
    /etc/init.d/dnsmasq stop
    ifconfig $port_out down
    ifconfig $port_out del $ip_prefix.1
    ifconfig $port_out up

    echo Sucess stop share wifi

    exit 0
}

ip_prefix=192.168.23 #wifi路由所用网段

#port_in is the network interface which connected to Internet, and default wlan1.
port_in=wlan1

#port_out is the network interface which will be setup AP, and default wlan0.
port_out=wlan0

if [ -n "$2" ]; then
    port_in=$2

    if [ -n "$3" ]; then
        port_out=$3
    fi
fi

case "$1" in
"help" )
    help ;;
"start" )
    start ;;
"stop" )
    stop ;;
*)
    help ;;
esac
### end the file /opt/sharewifi #########################################

2）设置开机自动启动，先编写开机启动的脚本。在/etc/init.d下建立文件sharewifi，文件内容如下：

### begin the file /etc/init.d/sharewifi ######################################### 
#!/bin/sh 
### BEGIN INIT INFO # Provides: sharewifi 
# Required-Start: $syslog 
# Required-Stop: $syslog 
# Default-Start: 2 3 4 5 
# Default-Stop: 0 1 6 
# Short-Description: starts the Wireless AP server 
# Description: starts the Wireless AP using start-stop-daemon 
### END INIT INFO
sharewifi=/opt/sharewifi
NAME=sharewifi
DESC=sharewifi

# Include nginx defaults if available
if [ ! -f $sharewifi ]; then
    echo "Can't find the file $sharewifi"
    exit 1
fi

case "$1" in
start)
    echo -n "Starting $DESC: "
    sh $sharewifi start eth0 wlan0
    echo "$NAME."
    ;;

stop)
    echo -n "Stopping $DESC: "
    sh $sharewifi stop eth0 wlan0
    echo "$NAME."
    ;;

restart)
    echo -n "Restarting $DESC: "
    sh $sharewifi stop eth0 wlan0
    sleep 1
    sh $sharewifi start eth0 wlan0
    echo "$NAME."
    ;;

*)
    echo "Usage: $NAME {start|stop|restart}" >&2
    exit 1
    ;;
esac

exit 0
### end the file /etc/init.d/sharewifi #########################################

3）执行以下命令，即可设置开机启动：

sudo update-rc.d /etc/init.d/sharewifi defaults