这几天在准备网络安装linux操作系统。最后决定用pxe + kickstart 的方式完成。原理、方案弄完了之后，开始搭建，结果被DHCP给挡住了。这不就得研究研究最简单最实用的DHCP使用方法。
* 红色的是必须有
* 绿色的是要注意
* 蓝色的是包安装时，要有的程序包
1. DHCP的实现
2. 配置文件实例
实例1
实例2
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1. DHCP的实现
DHCP服务必须给本网段提供一个地址池。
# yum -y install dhcp-devel
# rpm -aq | grep dhcp
dhcp-4.1.1-38.P1.el6.centos.i686
dhcp-devel-4.1.1-38.P1.el6.centos.i686
# cp /usr/share/doc/dhcp-4.1.1/dhcpd.conf.sample /etc/dhcp/dhcpd.conf
# vi dhcpd.conf
ddns-update-style interim;
default-lease-time 21600;
max-lease-time 43200;
option domain-name “test.com”;
option domain-name-servers 192.168.1.1,202.106.0.20;
subnet 192.168.1.0 netmask 255.255.2550 {
range 192.168.1.128 192.168.1.254;
option subnet-mask 255.255.255.0;
option routers 192.168.1.1;
}
host server01 {
hardware ethernet 0:c0:c3:22:46:81;
fixed-address 192.168.1.11;
option subnet-mask 255.255.255.0;
option routers 192.168.1.1;
}
subnet 117.34.70.0 netmask 255.255.255.0 {
default-lease-time 21600;
max-lease-time 43200;
option routers 117.34.70.1;
option subnet-mask 255.255.255.0;
}
一台主机有多块网卡，需要在某个网卡上启用DHCP服务时，需要配置如下：
# vi /etc/sysconfig/dhcpd
# Command line options here
DHCPDARGS="eth0"
------------------------------
2. 配置文件实例
简单的样例：（红色部分必须有）
# vi /etc/dhcp/dhcpd.conf
# dhcpd.conf
# Sample configuration file for ISC dhcpd
# option definitions common to all supported networks...
option domain-name "example.org";
option domain-name-servers ns1.example.org, ns2.example.org;
default-lease-time 600;
max-lease-time 7200;
# Use this to enble / disable dynamic dns updates globally.
ddns-update-style none;
# If this DHCP server is the official DHCP server for the local
# network, the authoritative directive should be uncommented.
#authoritative;
# Use this to send dhcp log messages to a different log file (you also
# have to hack syslog.conf to complete the redirection).
log-facility local7;
# No service will be given on this subnet, but declaring it helps the
# DHCP server to understand the network topology.
subnet 117.34.73.0 netmask 255.255.255.0 {
}
subnet 10.152.187.0 netmask 255.255.255.0 {
}
# vi /etc/dhcp/dhcpd.conf
default-lease-time 600;
max-lease-time 7200;
ddns-update-style none;
subnet 117.34.73.0 netmask 255.255.255.0 {
}
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* 注意：
● 如果主机网卡比较多，可以选择一块作为服务网卡。
vi /etc/sysconfig/dhcpd
# Command line options here
DHCPDARGS="em1:1"
● 提供服务的网卡必需是 非自动获取 的地址。
ifconfig eth0 172.16.40.129/25 up
● 服务提供的地址池必需包含本地提供服务的地址在里面。
● 地址池（range）不能与作用域（subnet）冲突。
● 其他的参数、选项没有也可以启动的。所以可以不设置，因为这里是为了网络安装。
● 如果配置了这里所说的最简单的 dhcp 服务，却无法启动。就剩下一个原因，每句后面有没有分号。
