udhcpc和udhcpd移植
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实现DHCP自动获取IP地址
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前提：系统已经实现DNS（即使用ping?www.baidu.com测试时能ping通）。
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：
~ # udhcpc
udhcpc (v0.9.9-pre) started
udhcpc[208]: udhcpc (v0.9.9-pre) started
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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
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。
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
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# udhcpc script edited by Tim Riker <Tim@Rikers.org>
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[ -z "$1" ] && echo "Error: should be called from udhcpc" && exit 1
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RESOLV_CONF="/etc/resolv.conf"
[ -n "$broadcast" ] && BROADCAST="broadcast $broadcast"
[ -n "$subnet" ] && NETMASK="netmask $subnet"
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case "$1" in
????????deconfig)
????????????????/sbin/ifconfig $interface?0.0.0.0
????????????????;;
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????????renew|bound)
????????????????/sbin/ifconfig $interface $ip $BROADCAST $NETMASK
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????????????????if [ -n "$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
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????????????????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
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exit 0
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~ # udhcpc
udhcpc (v0.9.9-pre) started
udhcpc[228]: udhcpc (v0.9.9-pre) started
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Sending discover...
udhcpc[228]: Sending discover...
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Sending select for 192.168.1.109...
udhcpc[228]: Sending select for 192.168.1.109...
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Lease of 192.168.1.109 obtained, lease time 86400
udhcpc[228]: Lease of 192.168.1.109 obtained, lease time 86400
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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
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例：udhcpc??-i??eth1?
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