DHCP服务器是为客户端机器分配IP地址的，所有分配的IP地址都保存在DHCP服务器的数据库中。
DHCP有两种配置方法：
地址池
地址池就是一段IP地址（例如，192.168.0.1 – 192.168.0.255）；DHCP服务器基于先到先服务原则。当DHCP客户端使用完某个IP地址之后，这个IP会重新回到地址池供其他机器使用。
MAC地址
DHCP服务器会通过客户端的MAC地址确定唯一网卡；DHCP客户端每次都会得到相同的配置。
1.安装DHCP服务
安装isc-dhcp-server：
$ sudo apt install isc-dhcp-server
DHCP的主要配置文件有两个，分别位于 /etc/default/isc-dhcp-server 和 /etc/dhcp/dhcpd.conf。
2.配置DHCP服务
首先配置 /etc/default/isc-dhcp-server 文件：
$ sudo vim /etc/default/isc-dhcp-server
配置DHCP服务使用哪个网卡接口：
INTERFACES="eth0"
配置 /etc/dhcp/dhcpd.conf 文件：
$ sudo vim /etc/dhcp/dhcpd.conf
文件内容如下：
#
#Sample configuration file for ISC dhcpd for Debian
#
#Attention: If /etc/ltsp/dhcpd.conf exists, that will be used as
# configuration file instead of this file.
#
#
# The ddns-updates-style parameter controls whether or not the server will
# attempt to do a DNS update when a lease is confirmed. We default to the
# behavior of the version 2 packages (‘none’, since DHCP v2 didn’t
# have support for DDNS.)
ddns-update-style none;
# option definitions common to all supported networks…
option domain-name-servers ns1.example.org, ns2.example.org;
option domain-name "yourdomainname.com";
default-lease-time 600;
max-lease-time 7200;
# 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.
# subnet10.152.187.0 netmask 255.255.255.0 {
# }
# This is a very basic subnet declaration.
subnet 10.0.0.0 netmask 255.255.255.0 {
range 10.0.0.150 10.0.0.253;
option routers 10.0.0.2;
option subnet-mask 255.255.255.0;
option broadcast-address 10.0.0.254;
option domain-name-servers 10.0.0.1, 10.0.0.2;
option ntp-servers 10.0.0.1;
option netbios-name-servers 10.0.0.1;
option netbios-node-type 8;
}
# 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”;
# }
# 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.
# hostfantasia {
# 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;
# }
# }
注意：替换域名和DNS域名服务器地址
3.配置完成之后重启DHCP服务：
$ sudo service isc-dhcp-server restart
4.查看dhcp是否正常运行：
$ sudo netstat -uap