前提：系统已经实现DNS（即使用ping [url=http://www.baidu.com测试时能ping/][color=#0000ff]www.baidu.com[/color]测试时能ping[/url]通）。1． 在内核中添加以下选项：Networking ---> [*] Networking support Networking options ---> Packet socket //添加.配置CONFIG_PACKET [ * ] IP: DHCP support //添加 [ * ] Network packet filtering (replaces ipchains) ---> //添加，后面子选项可不选，配置CONFIG_NETFILTER说明：若没选 Packet socket, [ * ] Network packet filtering (replaces ipchains) --->选项，在执行udhcpc命令时出现如下错误：~ # udhcpcudhcpc (v0.9.9-pre) startedudhcpc[208]: udhcpc (v0.9.9-pre) startedFATAL: couldn't listen on socket, Address family not supported by protocoludhcpc[208]: FATAL: couldn't listen on socket, Address family not supported by protocol2． Busybox中添加以下选项：Networking Utilities ---> udhcp Server/Client ---> [] udhcp Server (udhcpd) //在此不作服务端，故不选。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没编译相应选项，也可从网上下载相应文件，用arm-linux交叉编译得到udhcpd,udhcpc命令copy到usr/sbin下就可以了。我从 网上 下的udhcp_0.9.8cvs20050303.orig.tar.gz文件解压后修改Makefile文件在19行添加CROSS_COMPILE=arm-linux- 注释12行的COMBINED_BINARY=1，否则不生成udhcpc命令。3． 建相关配置文件从busybox的examples/udhcp/下copy simple.script文件到开发板/usr/share/udhcpc/下，并重命名为default.script，udhcp_0.9.8cvs20050303.orig.tar.gz中也有这样的文件。[root@localhost root]# vi usr/share/udhcpc/default.script #!/bin/sh# udhcpc script edited by Tim Riker [ -z "$1" ] && echo "Error: should be called from udhcpc" && exit 1RESOLV_CONF="/etc/resolv.conf"[ -n "$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 ;;esacexit 04． 重启开发板，执行udhcpc就可自动获取IP地址了，以下是执行udhcpc的输出信息：~ # udhcpcudhcpc (v0.9.9-pre) startedudhcpc[228]: udhcpc (v0.9.9-pre) startedSending 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 86400udhcpc[228]: Lease of 192.168.1.109 obtained, lease time 86400deleting routersroute: SIOC[ADD|DEL]RT: No such processadding dns 192.168.0.1~ # ping www.baidu.comPING www.a.shifen.com (220.181.38.4): 56 data bytes64 bytes from 220.181.38.4: icmp_seq=0 ttl=52 time=1219.0 ms[1] + Stopped ping www.baidu.com5． 如果是双网卡必须用参数指明例：udhcpc -i eth1
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