DHCP动态管理主机地址
DHCP(Dynamic Host Configuration Protocol)
DHCP是动态主机配置协议，动态主机设置协议是一个局域网的网络协议，使用UDP协议工作。该协议允许服务器向客户端动态分配 IP 地址和配置信息。DHCP协议支持C/S结构，主要分为客户端和服务端。
用于自动管理局域网内主机的IP地址，子网掩码、网关地址、Dns地址。
有效的提升IP地址的利用率，提高配置效率，降低管理与维护成本
安装
是否安装
npm -qa|grep dhcp
安装
yum install dhcp
查看配置文件内容
cat /etc/dhcp/dhcpd.conf
# DHCP Server Configuration file.
# see /usr/share/doc/dhcp*/dhcpd.conf.example
# see dhcpd.conf(5) man page
启动
service dhcpd start //RHEL6
systemctl restart dhcpd //RHEL7
配置
网段声明：以subnet字段开头
主机声明：以host字段开头
配置选项：由“option”引导，后面跟具体的配置关键字和对应的值
配置参数：由配置关键字和对应的值组成，总是以分号“；”结束
这是示例配置文件
# 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";
}
# 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;
}
}
全局配置
option domain-name 默认搜索区域
option domain-name-servers DNS服务器地址
option subnet-mask 定义客户端的子网掩码
ignore client-updates; 忽略客户端更新DNS记录
default-lease-time 默认租约时间（单位为秒）
表示客户端可以从DHCP服务器租用某个IP地址的默认时间max-lease-time 最大租约时间（单位为秒）
表示允许DHCP客户端请求的最大租约时间ddns-update-style 动态DNS更新模式
- none 不支持动态更新
- interim 互动更新模式
设置与DHCP服务相关联的DNS数据动态更新模式
网段配置
只作用指定的网段，可以声明网段可以有多个
- range 定义用于分配的IP地址池
- option routers 192.168.1.254; 定义客户端的网关地址
- option broadcast-address 192.168.1.255; 定义客户端的广播地址
- default-lease-time 600; 默认续约时间
- max-lease-time 7200; 最大续约时间
subnet 192.168.1.0 netmask 255.255.255.224 {
range 192.168.1.100 192.168.1.200; //IP地址池
option domain-name-servers ns1.internal.example.org;
option domain-name "internal.example.org";
option routers 192.168.1.254;
option broadcast-address 192.168.1.255;
default-lease-time 600;
max-lease-time 7200;
}
host主机声明（可选）
host声明用于设置单个主机的网络属性，通常用于为网络打印机或个别服务器分配固定的IP地址（保留地址），这些主机的共同特点是要求每次获取的IP地址相同，以确保服务的稳定性
- hardware 指定网卡接口的类型与MAC地址
- fixed-address 将某个固定的IP地址分配给指定主机
host prtsvr{ //设置Host关键字
hardware ethernet 00:0c:c3:32:23:21; //网卡地址
fixed-address 192.168.1.100; //指定保留的IP地址
}
启动
systemctl start dhcpd 启动Dhcp服务
systemctl enable dhcpd 加入开机启动项
