centos7 搭建DHCP服务器

 查看一下dhcp有没有安装

# rpm -qa dhcp

[root@localhost ~]# 
[root@localhost ~]# rpm -qa dhcp
[root@localhost ~]# 

 安装DHCP服务

# yum install dhcp -y

Installed:
  dhcp.x86_64 12:4.2.5-68.el7.centos.1                                                                                                                                     

Dependency Updated:
  dhclient.x86_64 12:4.2.5-68.el7.centos.1               dhcp-common.x86_64 12:4.2.5-68.el7.centos.1               dhcp-libs.x86_64 12:4.2.5-68.el7.centos.1              

Complete!
[root@localhost ~]# 

 查看dhcp的版本号

# rpm -qa dhcp

[root@localhost ~]# rpm -qa dhcp
dhcp-4.2.5-68.el7.centos.1.x86_64

查看一下dhcp.conf配置文件

# cat /etc/dhcp/dhcpd.conf 

[root@localhost ~]# cat /etc/dhcp/dhcpd.conf 
#
# DHCP Server Configuration file.
#   see /usr/share/doc/dhcp*/dhcpd.conf.example
#   see dhcpd.conf(5) man page
#
[root@localhost ~]# 

查看DHCP配置文件模板

# cat /usr/share/doc/dhcp-4.2.5/dhcpd.conf.example

#
# DHCP Server Configuration file.
#   see /usr/share/doc/dhcp*/dhcpd.conf.example
#   see dhcpd.conf(5) man page
#
# 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;         #默认租约时间
max-lease-time 7200;            #最大租约时间

# 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";
}

# 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;
  }
}

在配置文件中通常包括三部分，分别是声明（declarations）、参数(parameters)、选项(option)。

a、声明是用来描述dhcpd服务器中对网络布局的划分，是网络设置的逻辑范围。

B、参数用来表明如何执行任务，是否要执行任务或将哪些网络配置选项发送给客户。

c、选项是用来配置dhcp的可选参数，全部用option关键字作为开始。

配置实例

假设有一个公司的局域网，在该网络中用linux搭建dhcp服务器，网络中的ip地址网段为192.168.1.0，子网掩码为255.255.255.0，动态分配的ip地址区间为192.168.0.3~192.168.0.254，dns服务器地址为114.114.114.114，网关为192.168.1.1，公司总经理计算机的ip地址有特殊要求，设置ip地址为192.168.1.88。改如何进行配置？
我们只要把配置文件修改一下即可，如下：

# cat /etc/dhcp/dhcpd.conf 

[root@localhost ~]# cat /etc/dhcp/dhcpd.conf
#
# DHCP Server Configuration file.
# see /usr/share/doc/dhcp*/dhcpd.conf.example
# see dhcpd.conf(5) man page
#
subnet 192.168.1.0 netmask 255.255.255.0 {
range 192.168.1.3 192.168.1.254;
ddns-update-style none;
ignore client-updates;
default-lease-time 86400;
max-lease-time 518400;
option routers 192.168.1.55;
option domain-name-servers 114.114.114.114,8.8.8.8;
}
host fantasia {
hardware ethernet 00:0c:29:eb:31:23;
fixed-address 192.168.1.88;
}
[root@localhost ~]#

 重启DHCP服务器

# systemctl restart dhcpd

模拟总经理计算机

查看总经理计算机物理地址（MAC）

# cat /sys/class/net/eno16777736/address

[root@localhost ~]# cat /sys/class/net/eno16777736/address
00:0c:29:eb:31:23
[root@localhost ~]# 

确认一下IP

 参考博客：

https://blog.csdn.net/qq_18831583/article/details/79001796

https://blog.csdn.net/kongxx/article/details/43523225

http://www.bubuko.com/infodetail-1804738.html

end