嵌入式linux 开发板 dhcp ip

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<Tim@Rikers.org>

[ -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。