dhcp配置教程|dhcp|2|部署与设置

约定：本实验中使用过的机器为centos8.0_x86_64系统，计算机名称:localhost.localdomain,ip地址192.168.11.16/24.请关闭防火墙和selinux，我来为大家讲解一下关于dhcp配置教程?跟着小编一起来看一看吧!

dhcp配置教程

四、dhcp服务器部署

约定：本实验中使用过的机器为centos8.0_x86_64系统，计算机名称:localhost.localdomain,ip地址192.168.11.16/24.请关闭防火墙和selinux。

4.1）dhcp安装

[root@localhost ~]# dnf -y install dhcp-server

4.2）dhcp配置文件详解

默认情况下，dhcp服务并没有提供配置文件，只是给提供了一个demo,存放在/usr/share/doc/dhcp-server/目录下.我们将demo文件拷贝到/etc/dhcp目录下，并且命名为dhcpd.conf。

[root@localhost ~]# cp /usr/share/doc/dhcp-server/dhcpd.conf.example /etc/dhcp/dhcpd.conf cp：是否覆盖"/etc/dhcp/dhcpd.conf" y

配置文件详解

[root@localhost ~]# cat /etc/dhcp/dhcpd.conf# #号代表注释# dhcp服务配置文件分为全局配置和作用域配置，很好区分：subnet的就是作用域 不在subnet里面的就是全局设置。# dhcpd.conf## sample configuration file for isc dhcpd##dns全局选项，指定dns服务器的地址，可以是ip，也可以是域名。# option definitions common to all supported networks...# dns的域名option domain-name "example.org";#具体的dns服务器option domain-name-servers ns1.example.org, ns2.example.org;#默认租约为600sdefault-lease-time 600;#最大租约为7200s，客户机会在default-lease-time快到期时向服务器续租，如果此时客户机死机/重启，而默认租约时间到期了，服务器并不会立即回收ip地址，而是等到最大租约时间到期，客户机还没有过来续约，才会回收ip地址。max-lease-time 7200;#动态dns更新方式(none:不支持；interim:互动更新模式；ad-hoc:特殊更新模式)# use this to enble / disable dynamic dns updates globally.#ddns-update-style none;#如果该dhcp服务器是本地官方dhcp就将此选项打开，避免其他dhcp服务器的干扰。#当一个客户端试图获得一个不是该dhcp服务器分配的ip信息，dhcp将发送一个拒绝消息，而不会等待请求超时。当请求被拒绝，客户端会重新向当前dhcp发送ip请求获得新地址。保证ip是自己发出去的## 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).# 日志级别log-facility local7;# no service will be given on this subnet, but declaring it helps the # dhcp server to understand the network topology.#作用域相关设置指令#subnet 定义一个作用域#netmask 定义作用域的掩码#range 允许发放的ip范围#option routers 指定网关地址#option domain-name-servers 指定dns服务器地址#option broadcast-address 广播地址###案例:定义一个作用域 网段为10.152.187.0 掩码为255.255.255.0#此作用域不提供任何服务subnet 10.152.187.0 netmask 255.255.255.0 {}# this is a very basic subnet declaration.#案例:定义一个基本的作用域#网段10.254.239.0 掩码255.255.255.224#分发范围10.254.239.10-20#网关为rtr-239-0-1.example.org, rtr-239-0-2.example.orgsubnet 10.254.239.0 netmask 255.255.255.224 { range 10.254.239.10 10.254.239.20; option routers rtr-239-0-1.example.org, rtr-239-0-2.example.org;}# this declaration allows bootp clients to get dynamic addresses,# which we don't really recommend.#案例:允许采用bootp协议的客户端动态获得地址#bootp dhcp的前身#bootp用于无盘工作站的局域网中，可以让无盘工作站从一个中心服务器上获得ip地址。通过bootp协议可以为局域网中的无盘工作站分配动态ip地址，#这样就不需要管理员去为每个用户去设置静态ip地址。subnet 10.254.239.32 netmask 255.255.255.224 { range dynamic-bootp 10.254.239.40 10.254.239.60; option broadcast-address 10.254.239.31; option routers rtr-239-32-1.example.org;}#案例:一个简单的作用域案例# a slightly different configuration for an internal subnet.subnet 10.5.5.0 netmask 255.255.255.224 { range 10.5.5.26 10.5.5.30; option domain-name-servers ns1.internal.example.org; option domain-name "internal.example.org"; option routers 10.5.5.1; option broadcast-address 10.5.5.31; default-lease-time 600; max-lease-time 7200;}# hosts which require special configuration options can be listed in# host statements. if no address is specified, the address will be# allocated dynamically (if possible), but the host-specific information# will still come from the host declaration.##保留地址:可以将指定的ip分发给指定的机器，根据网卡的mac地址来做触发#host: 启用保留。#hardware:指定客户端的mac地址#filename:指定文件名#server-name:指定下一跳服务器地址#fixed-address: 指定保留ip地址###案例:这个案例中分发给客户端的不是ip地址信息，而是告诉客户端去找toccata.fugue.com服务器，并且下载vmunix.passacaglia文件host passacaglia { hardware ethernet 0:0:c0:5d:bd:95; filename "vmunix.passacaglia"; server-name "toccata.fugue.com";}# fixed ip addresses can also be specified for hosts. these addresses# should not also be listed as being available for dynamic assignment.# hosts for which fixed ip addresses have been specified can boot using# bootp or dhcp. hosts for which no fixed address is specified can only# be booted with dhcp, unless there is an address range on the subnet# to which a bootp client is connected which has the dynamic-bootp flag# set.# 案例:保留地址，将指定ip(fantasia.fugue.com对应的ip)分给指定客户端网卡(mac:08:00:07:26:c0:a5)host fantasia { hardware ethernet 08:00:07:26:c0:a5; fixed-address fantasia.fugue.com;}#超级作用域#超级作用域是dhcp服务中的一种管理功能，使用超级作用域，可以将多个作用域组合为单个管理实体。# you can declare a class of clients and then do address allocation# based on that. the example below shows a case where all clients# in a certain class get addresses on the 10.17.224/24 subnet, and all# other clients get addresses on the 10.0.29/24 subnet.#在局域网中，可以配置策略根据各个机器的具体信息分配ip地址和其他的网络参数，客户机的具体信息：客户机能够给dhcp服务提供的信息由有两个，#第一个就是网卡的dhcp-client-identifier（mac地址），#第二个就是设备的vendor-class-identifier。#管理员可以根据这两个信息给不同的机器分组。#案例:#按client某种类型分组dhcp,而不是按物理接口网段#例子: sunw 分配地址段10.17.224.0/24# 非sunw的主机,分配地址段10.0.29.0/24#定义一个dhcp类:foo#request广播中vendor-class-identifier字段对应的值前四个字节如果是"sunw",则视合法客户端.class "foo" { match if substring (option vendor-class-identifier, 0, 4) = "sunw";}#定义一个超级作用域: 224-29shared-network 224-29 {#定义第一个作用域 subnet 10.17.224.0 netmask 255.255.255.0 { option routers rtr-224.example.org; }#定义第二个作用域 subnet 10.0.29.0 netmask 255.255.255.0 { option routers rtr-29.example.org; }#关连池,如果客户端匹配foo类，将获得该池地址 pool { allow members of "foo"; range 10.17.224.10 10.17.224.250; }#关连池,如果客户端配置foo类，则拒绝获得该段地址 pool { deny members of "foo"; range 10.0.29.10 10.0.29.230; }}

4.3）dhcp启动

[root@localhost ~]# systemctl enable dhcpdcreated symlink from /etc/systemd/system/multi-user.target.wants/dhcpd.service to /usr/lib/systemd/system/dhcpd.service.[root@localhost ~]# systemctl start dhcpd注意：可能发现无法启动dhcp服务，原因是dhcp在启动的时候检查配置文件，发现并没有有效作用域（和服务器同网段的作用域）。

总结

dhcp服务如何安装

dhcp配置文件

配置文件如何设置

如何启动服务

重点：dhcp服务如何安装，dhcp的配置文件及含义，服务如何启动

难点：字段内容较多，各字段含义要明确

,