http://blog.chinaunix.net/uid-17188120-id-2820863.html

1．  在核心中新增以下選項：

Networking  --->

   [*] Networking support  

      Networking options  ---> 

          <* > Packet socket                 //新增.配置CONFIG_PACKET

          [ * ]     IP: DHCP support         //新增

          [ * ] Network packet filtering (replaces ipchains)  --->    //

說明：若沒選<* > Packet socket, [ * ] Network packet filtering (replaces ipchains)  --->選項，在執行udhcpc命令時出現如下錯誤：

~ # udhcpc

udhcpc (v0.9.9-pre) started

udhcpc[208]: udhcpc (v0.9.9-pre) started

FATAL: couldn't listen on socket, Address family not supported by protocol

udhcpc[208]: FATAL: couldn't listen on socket, Address family not supported by protocol

2．  Busybox中新增以下選項：

Networking Utilities  --->

   udhcp Server/Client  --->

        [] udhcp Server (udhcpd)       //在此不作服務端，故不選。生成udhcpd命令

        [*] udhcp Client (udhcpc)       //生成udhcpc命令

        [ ] Lease display utility (dumpleases)                        

        [ ]   Log udhcp messages to syslog (instead of stdout)        

        [ ]   Compile udhcp with noisy debugging messages

若busybox沒編譯相應選項，也可從網上下載相應檔案，用arm-linux交叉編譯得到udhcpd,udhcpc命令copy到usr/sbin下就可以了。

我從 網上  下的udhcp_0.9.8cvs20050303.orig.tar.gz檔案

解壓後修改Makefile檔案

在19行新增CROSS_COMPILE=arm-linux-  

註釋12行的COMBINED_BINARY=1，否則不生成udhcpc命令。

3．  建相關配置檔案

從busybox的examples/udhcp/下copy  simple.script檔案到開發板/usr/share/udhcpc/下，並重命名為default.script，udhcp_0.9.8cvs20050303.orig.tar.gz中也有這樣的檔案。

[[email protected] root]# vi usr/share/udhcpc/default.script

#!/bin/sh

# udhcpc script edited by Tim Riker <[email protected]>

[ -z "$1" ] && echo "Error: should be called from udhcpc" && exit 1

RESOLV_CONF="/etc/resolv.conf"

[ -n "$broadcast" ] && BROADCAST="broadcast $broadcast"

[ -n "$subnet" ] && NETMASK="netmask $subnet"

case "$1" in

        deconfig)

                /sbin/ifconfig $interface 0.0.0.0

                ;;

        renew|bound)

                /sbin/ifconfig $interface $ip $BROADCAST $NETMASK

                if [ -n "$router" ] ; then

                        echo "deleting routers"

                        while route del default gw 0.0.0.0 dev $interface ; do

                                :

                        done

                        for i in $router ; do

                                route add default gw $i dev $interface

                        done

                fi

                echo -n > $RESOLV_CONF

                [ -n "$domain" ] && echo search $domain >> $RESOLV_CONF

                for i in $dns ; do

                        echo adding dns $i

                        echo nameserver $i >> $RESOLV_CONF

                done

                ;;

esac

exit 0

4．  重啟開發板，執行udhcpc就可自動獲取IP地址了，以下是執行udhcpc的輸出資訊：

~ # udhcpc

udhcpc (v0.9.9-pre) started

udhcpc[228]: udhcpc (v0.9.9-pre) started

Sending discover...

udhcpc[228]: Sending discover...

Sending select for 192.168.1.109...

udhcpc[228]: Sending select for 192.168.1.109...

Lease of 192.168.1.109 obtained, lease time 86400

udhcpc[228]: Lease of 192.168.1.109 obtained, lease time 86400

deleting routers

route: SIOC[ADD|DEL]RT: No such process

adding dns 192.168.0.1

~ # ping www.baidu.com

PING www.a.shifen.com (220.181.38.4): 56 data bytes

64 bytes from 220.181.38.4: icmp_seq=0 ttl=52 time=1219.0 ms

[1] + Stopped                    ping www.baidu.com

5．  如果是雙網絡卡必須用引數指明

例：udhcpc  -i  eth1