# DHCP 简单使用
# 简介
动态主机设置协议（英语：Dynamic Host Configuration Protocol，缩写：DHCP）是一个用于IP (opens new window)网络的网络协议 (opens new window)，位于OSI模型 (opens new window)的应用层 (opens new window)，使用UDP (opens new window)协议工作，主要有两个用途：
- 用于内部网或网络服务供应商自动分配IP地址 (opens new window)给用户
- 用于内部网管理员对所有电脑作中央管理
服务器端工具有:
- dhcp: 只提供
dhcp服务 - dnsmasq: 轻量级,提供
dhcp和dns服务
# 安装与配置文件
yum install -y dhcp
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通过rpm -ql dhcp可以了解到
dhcp提供两个程序,一个是dhcpd(dhcp服务器端守护进程),另一个是dhcrelay(dhcp中继代理服务)dhcp有三个UNIT FILE启动服务时应当分清出自己要启动的服务
配置文件/etc/dhcp/dhcp.conf:
该配置文件默认内容为空,程序包提供了示例配置文件,我们可以直接拿来修改修改
cp /usr/share/doc/dhcp-4.2.5/dhcpd.conf.example ./dhcpd.conf
# option definitions common to all supported networks...
# 全局配置
option domain-name "agou-ops.com";
option domain-name-servers 192.168.159.2; # 指定默认DNS服务器
option routers 192.168.99.1; # 指定默认路由
default-lease-time 43200;
max-lease-time 86400;
log-facility local7;
# 子网配置
subnet 192.168.0.0 netmask 255.255.0.0 {
range 192.168.99.101 192.168.99.120;
}
# 为特定主机分配固定IP地址
host apex {
hardware ethernet 00:0c:29:b8:73:9e;
fixed-address 192.168.99.99;
}
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修改完配置文件需要重启dhcpd,systemctl restart dhcpd
查看dhcpd 工作情况可以查看其分配情况:
[root@master ~]\# less /var/lib/dhcpd/dhcpd.leases
# The format of this file is documented in the dhcpd.leases(5) manual page.
# This lease file was written by isc-dhcp-4.2.5
lease 192.168.99.101 {
starts 0 2020/04/19 19:53:55;
ends 1 2020/04/20 07:53:55;
tstp 1 2020/04/20 07:53:55;
cltt 0 2020/04/19 19:53:55;
binding state active;
next binding state free;
rewind binding state free;
hardware ethernet 00:0c:29:ad:e1:01;
client-hostname "master";
}
server-duid "\000\001\000\001&/d^\000\014)\255\341\001";
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# dhclient 使用
默认情况下,dhcp服务端监听的端口是udp的67号端口,客户端dhclient则监听udp的68号端口
在前台查看网络地址信息的获取情况(第二次执行):
[root@node01 ~]\# dhclient -d # -d 运行在前台,需要特别注意
Internet Systems Consortium DHCP Client 4.2.5
Copyright 2004-2013 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/
Listening on LPF/ens33/00:0c:29:d1:17:17
Sending on LPF/ens33/00:0c:29:d1:17:17
Sending on Socket/fallback
DHCPREQUEST on ens33 to 255.255.255.255 port 67 (xid=0x2447b4d8)
DHCPACK from 192.168.159.129 (xid=0x2447b4d8)
bound to 192.168.99.103 -- renewal in 18303 seconds.
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可以看到从本地局域网中的DHCP服务器中获取到了IP地址等相关信息.
# 参考链接
- redhat-dhcp服务器:https://access.redhat.com/documentation/zh-cn/red_hat_enterprise_linux/7/html/networking_guide/sec-dhcp-configuring-server
- dhcp-中继服务器:https://access.redhat.com/documentation/zh-cn/red_hat_enterprise_linux/7/html/networking_guide/dhcp-relay-agent