DHCP程序运行与调试实现的目标：开机时自动获取IP地址，若没有可用的IP地址，选用autoip；或者选用静态配置的ip 地址。

DHCP客户端程序有多种，本系统选用的busybox下的dhcpc。

［1］修改内核配置；在内核中添加以下选项：Networking --->[*] Networking supportNetworking 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？--- Network packet filtering framework (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 (v-pre) startedudhcpc[208]: udhcpc (v-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 protocol［2］修改busybox配置，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_cvs20050303.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］运行程序：up-tech:/sbin #./udhcpcudhcpc (v1.15.3) startedSending discover...Sending select for 192.168.1.102...Sending discover...Sending select for 192.168.1.101...Lease of 192.168.1.101 obtained, lease time 7200［4］将busybox目录下：examples/udhcp/simple.script拷贝到根目录文件夹/usr/share/udhcpc/default.script。

覆盖掉原始文件。

重新制作根目录。

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_cvs20050303.orig.tar.gz中也有这样的文件。

修改ip没有成功！up-tech:/sbin #./udhcpcudhcpc (v1.15.3) startedSetting IP address 0.0.0.0 on eth0<1>/usr/share/udhcpc/default.script: line 45: ifconfig: not foundSending discover...Sending select for 192.168.1.101...Lease of 192.168.1.101 obtained, lease time 7200Setting IP address 192.168.1.101 on eth0<2>/usr/share/udhcpc/default.script: line 45: ifconfig: not foundDeleting routers<3>/usr/share/udhcpc/default.script: line 45: route: not foundAdding router 192.168.1.1<4>/usr/share/udhcpc/default.script: line 45: route: not foundRecreating /etc/resolv.conf<5>/usr/share/udhcpc/default.script: line 45: can't create /etc/resolv.conf-872: Rm<6>/usr/share/udhcpc/default.script: line 45: can't create /etc/resolv.conf-872: RmAdding DNS server 192.168.1.1<7>/usr/share/udhcpc/default.script: line 45: can't create /etc/resolv.conf-872: Rm<8>mv: cannot rename '/etc/resolv.conf-872': No such file or directoryenv查看环境变量PATH="/bin:/usr/bin:/opt/bluez/bin:/opt/bluez/sbin"也可以通过echo $PATH 查看。

busybox生成的在/bin:/sbin:/usr/bin:/usr/sbin。

在sbin下的命令都得不到执行。

修改：/etc/profile将line4：export PATH=/bin:/usr/bin:改成export PATH=/bin:/sbin:/usr/bin:usr/sbinline29，line30# Bluez bin/libexport LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/opt/bluez/libexport PATH=$PATH:/opt/bluez/bin:/opt/bluez/sbin改成# Bluez bin/libexport LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/libexport PATH=$PATH:/usr/bin:/usr/sbin错误<5><6><7><8>:create /etc/resolv.conf-872: 根文件系统不能创建resolv.conf。

在开法板的/etc目录下可以找到resolv.conf文件。

错误原因在于CromFS是只读文件系统，不能创建和修改文件。

修改方法：加载yaffs文件系统，将需要读写的文件改成可读写方式。

先不修改。

［5］修改环境变量～up-tech:~ #echo $PATH/bin:/sbin:/usr/bin:usr/sbin:/usr/bin:/usr/sbin运行DHCPC客户端程序；up-tech:~ #udhcpcudhcpc (v1.15.3) startedSetting IP address 0.0.0.0 on eth0Sending discover...Sending select for 192.168.1.101...Lease of 192.168.1.101 obtained, lease time 7200Setting IP address 192.168.1.101 on eth0Deleting routersroute: SIOCDELRT: No such processAdding router 192.168.1.1Recreating /etc/resolv.conf/usr/share/udhcpc/default.script: line 45: can't create /etc/resolv.conf-871: Rm /usr/share/udhcpc/default.script: line 45: can't create /etc/resolv.conf-871: Rm Adding DNS server 192.168.1.1/usr/share/udhcpc/default.script: line 45: can't create /etc/resolv.conf-871: Rmmv: cannot rename '/etc/resolv.conf-871': No such file or directory 查看ip地址是否修改成功；up-tech:~ #ifconfigeth0 Link encap:Ethernet HWaddr 08:00:3E:26:0A:5Binet addr:192.168.1.101 Bcast:192.168.1.255 Mask:255.255.255.0UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1RX packets:236 errors:0 dropped:0 overruns:0 frame:0TX packets:2 errors:0 dropped:0 overruns:0 carrier:0collisions:0 txqueuelen:1000RX bytes:19801 (19.3 KiB) TX bytes:1180 (1.1 KiB)Interrupt:18 Base address:0xe000 DMA chan:fflo Link encap:Local Loopbackinet addr:127.0.0.1 Mask:255.0.0.0UP LOOPBACK RUNNING MTU:16436 Metric:1RX packets:0 errors:0 dropped:0 overruns:0 frame:0TX packets:0 errors:0 dropped:0 overruns:0 carrier:0collisions:0 txqueuelen:0RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)［6］开发板直接与PC机连接up-tech login: rootid: applet not found-bash: [: -eq: unary operator expectedid: applet not foundup-tech:~ #ifconfigeth0 Link encap:Ethernet HWaddr 08:00:3E:26:0A:5Binet addr:192.168.0.195 Bcast:192.168.0.255UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1RX packets:34 errors:0 dropped:0 overruns:0 frame:0TX packets:0 errors:0 dropped:0 overruns:0 carrier:0collisions:0 txqueuelen:1000RX bytes:3581 (3.4 KiB) TX bytes:0 (0.0 B)Interrupt:18 Base address:0xe000 DMA chan:fflo Link encap:Local Loopbackinet addr:127.0.0.1 Mask:255.0.0.0UP LOOPBACK RUNNING MTU:16436 Metric:1RX packets:0 errors:0 dropped:0 overrunTX packets:0 errors:0 dropped:0 overruns:0 carrier:0collisions:0 txqueuelen:0RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)up-tech:~ #udhcpcudhcpc (v1.15.3) startedSetting IP address 0.0.0.0 on eth0Sending discover...Sending discover...Sending discover...Sending discover...Sending discover...Sending discover...Sending discover...Sending discover...Sending discover...若使用DHCP，会修改原始的IP地址；注意问题：DHCP获取不到的话，原始的IP 设置也会被修改。