嵌入式Linux通过DHCP自动获取IP地址的方法 1．  在编译嵌入式Linux内核时添加以下选项： Networking  --->    [*] Networkingsupport         Networkingoptions  --->           <* > Packet socket                //添加.配置CONFIG_PACKET          [ * ]     IP: DHCPsupport         //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<* > Packetsocket, [ * ] Network packet filtering (replaces ipchains)  --->选项，在执行udhcpc命令时出现如下错误： ~ # udhcpc udhcpc (v0.9.9-pre)started udhcpc[208]: udhcpc (v0.9.9-pre)started FATAL: couldn't listen on socket, Addressfamily not supported by protocol udhcpc[208]: FATAL: couldn't listen onsocket, Address family not supported by protocol   2．  在编译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 ofstdout)                [ ]   Compile udhcp with noisy debugging messages   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]# viusr/share/udhcpc/default.script #!/bin/sh # udhcpc script edited by Tim Riker [ -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 deldefault 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： ~ # 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 for192.168.1.109... Lease of 192.168.1.109 obtained, lease time86400 udhcpc[228]: Lease of 192.168.1.109obtained, lease time 86400 deleting routers route: SIOC[ADD|DEL]RT: No such process adding dns 192.168.0.1   5．  如果是双网卡必须用参数指明 例：udhcpc  -i eth1    附：如何在LinuxPE中用脚本获取DHCP Server的IP地址 Inside the LinuxPE environment, afterenable udhcp service:
/sbin/udhcpc start
that
Server_IP=`cat /tmp/resolv.conf | cut -d "     用busybox生成的udhcpc命令,关键要把busybox的目录下examples/udhcp/simple.script 脚本文件做为default.script拷贝,使用下面的命令 cp /examples/udhcpc/simple.script /usr/share/udhcpc/default.script
同时要在编译busybox时选中使用usr的选项，否则需要把simple.script拷贝到 /share/man/udhcp/default.script
内核选项里也要把DHCP的选项加上。