安装配置DHCP

本次实验采用CentOS7

1.检查

在安装DHCP之前先使用rpm命令查看系统中已有的DHCP软件包

rpm -qa | grep dhcp

由此可知，系统中尚未安装DHCP软件包

2.安装

我们可以使用yum命令为系统安装DHCP软件包

yum -y install dhcp

安装完成后再次检查可以看到DHCP软件包

3.配置dhcp配置文件

我们在上面的安装过程中已经知道了当前系统中的dhcp软件包版本为 4.2.5

因此去往路径/usr/share/doc/dhcp-4.2.5/dhcpd.conf.example

---

这里是一些介绍，想要直接配置的可以跳过

# 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 10.152.187.0 netmask 255.255.255.0 {
}# This is a very basic subnet declaration.subnet 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.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;
}# 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.host passacaglia {hardware ethernet 0:0:c0:5d:bd:95;filename "vmunix.passacaglia";server-name "toccata.fugue.com";
}1,1          顶端# 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.
host fantasia {hardware ethernet 08:00:07:26:c0:a5;fixed-address fantasia.fugue.com;
}# 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.class "foo" {match if substring (option vendor-class-identifier, 0, 4) = "SUNW";
}shared-network 224-29 {subnet 10.17.224.0 netmask 255.255.255.0 {option routers rtr-224.example.org;}subnet 10.0.29.0 netmask 255.255.255.0 {option routers rtr-29.example.org;}pool {allow members of "foo";range 10.17.224.10 10.17.224.250;}pool {deny members of "foo";range 10.0.29.10 10.0.29.230;}
}100,1        底端

DHCP服务参数

参数	说明
ddns-update-style	配置全局启用/禁用动态DNS更新
authentication	拒绝未经验证的IP 地址的请求
default-lease-time	指定租约时间的最大值
max-lease-time	指定租约时间的最小值
hardware	指定网卡接口类型和MAC地址
fixed-address	为客户端主机指定固定IP

DHCP服务声明

声明	说明
subnet	指定子网作用域
range	指定子网作用域
allows bootp / deny bootp	响应激活查询/ 拒绝响应激活查询
allow booting / deny booting	响应激活查询/ 拒绝响应激活查询
host	指定保留主机
filename	指定启动文件
netx-server	设置文件共享服务器
shared-network	为客户端主机指定固定IP

DHCP服务选项

选项	说明
domain-name	设置客户端的DNS域名
domain-name-servers	设置DNS服务器的IP地址
host-name	设置客户端的主机名
subnet-mask	设置客户端的子网掩码
routers	设置客户端网关IP地址
broadcast-address	设置客户端的广播地址

---

简单的编写一个配置文件

allow booting;
#分配子网，网段为192.168.138.0 子网掩码为255.255.255.0
subnet 192.168.138.0 netmask 255.255.255.0 {range 192.168.138.128 192.168.138.254; #设置子网的IP地址取值范围#设置为客户端分配的DNS服务器地址option domain-name-servers 192.168.138.2;#设置客户端的DNS域名option domain-name "internal.example.org";#设置网关地址option routers 192.168.138.2;#设置最短租约时常default-lease-time 3600;#设置最长租约时长max-lease-time 7200;#设置文件共享服务器地址next-server 192.168.138.9#设置文件服务器上共享的启动文件名称filename "pxelinux.0"
}

需要注意:

1.在格式上配置文件应该与模板中提供的格式相同

2.在内容上，地址池的IP地址范围应该在子网范围内，本机网卡IP应在地址池范围之内

所有配置完成之后，在客户端上将网卡的配置文件中的BOOTPROTO项的值设为dhcp

再重启网络服务即可