DHCP（Dynamic Host Configuration Protocol，动态主机配置协议）通常被应用在大型的局域网络环境中，主要作用是集中的管理、分配IP地址，使网络环境中的主机动态的获得IP地址、 Gateway地址、DNS服务器地址等信息，并能够提升地址的使用率。
C/S 模式
Server：DHCP Server（运行dhcp服务）UDP服务：67
Client：DHCP Client(运行dhcp程序) UDP服务：68
udp：适合发送较小的数据报文，且对时效性要求较高
工作流程如下图所示：
当客户端获取不到有效地址时候 dhcp会发一个 169.254.X.X 作为本地地址
安装配置：
[root@marvin ~]# yum install dhcp
配置文件：
[root@marvin dhcp]# pwd /etc/dhcp [root@marvin dhcp]# cp /usr/share/doc/dhcp-4.1.1/dhcpd.conf.sample dhcpd.conf
配置文件说明：
[root@marvin dhcp]# vim dhcpd.conf
#log-facility local7; #日志/var/log/boot.log
#全局地址分配属性：option开头
#option domain-name #域名搜索列表，类似于/etc/resolv.conf中的searchoption
#domain-name-servers #域名服务器地址，多个的话用逗号隔开
#option routers #网关
#option broadcasst-address #广播地址
#option subnet-mask #子网掩码
#default-lease-time #默认租约期限，一般这项生效（以秒为单位）
#max-lease-time #最大租约期限（以秒为单位）
#range START_IP END_IP #地址池（可以在subnet中指定多个range，但多个range所定义IP范围不能重复）
#子网配置：通常每个作用域通过一个subnet定义
#subnet NETWORK_ADDR netmask NETMASK {
# range
# option routers
# }
#主机配置：通常为某特定MAC地址固定的分配一个地址
# host ‘HOST ID‘ {
# hardware ethernet 08:00:07:26:c0:a5;
# fixed-address IP;
# }服务进程：
[root@marvin ~]# /etc/init.d/dhcpd restart Shutting down dhcpd: [ OK ] Starting dhcpd: [ OK ] [root@marvin ~]# ps -ef |grep dhcp dhcpd 1952 1 0 03:53 ? 00:00:00 /usr/sbin/dhcpd -user dhcpd -group dhcpd
服务端口：
[root@marvin ~]# ss -lnup
State Recv-Q Send-Q Local Address:Port Peer Address:Port
UNCONN 0 0 *:67 *:* users:(("dhcpd",1952,7))
UNCONN 0 0 *:68 *:* users:(("dhclient",2066,6))demo：
[root@marvin dhcp]# vim dhcpd.conf
#全局变量
option domain-name "marvin";
option domain-name-servers 114.114.114.114,8.8.8.8;
option routers 192.168.1.1;
option broadcast-address 192.168.1.255;
default-lease-time 600;
max-lease-time 7200;
log-facility local7;
subnet 192.168.1.0 netmask 255.255.255.0{
range 192.168.1.201 192.168.1.240;
host sherry{ ＃根据主机mac配置固定ip
hardware ethernet 00:0c:29:3c:e2:60;#sherry主机的mac地址
fixed-address 192.168.1.221; #给sherry主机分配固定ip
}
}log：
服务排错：
[root@marvin /]# tail -f /var/log/messages May 19 06:24:47 marvin dhcpd: Dynamic and static leases present for 192.168.1.221. May 19 06:24:47 marvin dhcpd: Remove host declaration sherry or remove 192.168.1.221 May 19 06:24:47 marvin dhcpd: from the dynamic address pool for 192.168.1.0/24 May 19 06:24:47 marvin dhcpd: DHCPREQUEST for 192.168.1.221 from 00:0c:29:3c:e2:60 via eth1 May 19 06:24:47 marvin dhcpd: DHCPACK on 192.168.1.221 to 00:0c:29:3c:e2:60 via eth1 May 19 06:29:43 marvin dhcpd: Dynamic and static leases present for 192.168.1.221. May 19 06:29:43 marvin dhcpd: Remove host declaration sherry or remove 192.168.1.221 May 19 06:29:43 marvin dhcpd: from the dynamic address pool for 192.168.1.0/24 May 19 06:29:43 marvin dhcpd: DHCPREQUEST for 192.168.1.221 from 00:0c:29:3c:e2:60 via eth1 May 19 06:29:43 marvin dhcpd: DHCPACK on 192.168.1.221 to 00:0c:29:3c:e2:60 via eth1
服务log：
[root@marvin /]# tail -f /var/log/boot.log May 19 06:24:47 marvin dhcpd: Dynamic and static leases present for 192.168.1.221. May 19 06:24:47 marvin dhcpd: Remove host declaration sherry or remove 192.168.1.221 May 19 06:24:47 marvin dhcpd: from the dynamic address pool for 192.168.1.0/24 May 19 06:24:47 marvin dhcpd: DHCPREQUEST for 192.168.1.221 from 00:0c:29:3c:e2:60 via eth1 May 19 06:24:47 marvin dhcpd: DHCPACK on 192.168.1.221 to 00:0c:29:3c:e2:60 via eth1 May 19 06:29:43 marvin dhcpd: Dynamic and static leases present for 192.168.1.221. May 19 06:29:43 marvin dhcpd: Remove host declaration sherry or remove 192.168.1.221 May 19 06:29:43 marvin dhcpd: from the dynamic address pool for 192.168.1.0/24 May 19 06:29:43 marvin dhcpd: DHCPREQUEST for 192.168.1.221 from 00:0c:29:3c:e2:60 via eth1 May 19 06:29:43 marvin dhcpd: DHCPACK on 192.168.1.221 to 00:0c:29:3c:e2:60 via eth1
原文地址：http://9173436.blog.51cto.com/9163436/1775052
