linux服务DHCP详解

Posted 2020-10-03

DHCP -----   Dynamic Host Configuration Protocol   动态主机配置协议

应用层协议

作用：为客户端分配IP信息 

原理：

1、客户端发送DHCP Discovery探索DHCP服务器 

2、DHCP服务器发送DHCP Offer (IP/NETMASK/GATEWAY/DNS)

3、客户端发送DHCP Request

4、DHCP服务器发送DHCP ACK

5、客户端发送Gratuation ARP用于检测IP地址是否冲突 

软件：dhcp

配置文件：/etc/dhcp/dhcpd.conf

服务：dhcpd

端口：67/udp(DHCP服务端端口) , 68/udp(DHCP客户端端口) 

示例：配置DHCP服务器 

环境描述：

隔离网络： Lan1     网段：192.168.87.0/24

DHCP服务器：   192.168.87.101, dhcpserver.linux.com 

客户端：

Linux

windows XP 

1) 配置主机名，IP地址

[[email protected] ~]# hostnamectl set-hostname server.linux.com 

[[email protected] ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth0 

# Generated by dracut initrd

DEVICE=eth0

NAME=eth0

ONBOOT=yes

BOOTPROTO=none

TYPE=Ethernet

IPADDR=192.168.87.101

NETMASK=255.255.255.0

[[email protected] ~]# systemctl restart network

[[email protected] ~]# systemctl restart NetworkManager

[[email protected] ~]# ip addr show eth0

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

    link/ether 52:54:00:71:3b:1c brd ff:ff:ff:ff:ff:ff

    inet 192.168.87.101/24 brd 192.168.87.255 scope global eth0

       valid_lft forever preferred_lft forever

    inet6 fe80::5054:ff:fe71:3b1c/64 scope link 

       valid_lft forever preferred_lft forever

2) 配置yum源，安装DHCP软件  

[[email protected] ~]# mkdir /etc/yum.repos.d/default

[[email protected] ~]# mv /etc/yum.repos.d/CentOS-* /etc/yum.repos.d/default

[[email protected] ~]# vim /etc/yum.repos.d/local.repo

[local]

name=localsrc

baseurl=file:///mnt

enabled=1

gpgcheck=0

[[email protected] ~]# mount /dev/cdrom /mnt/

[[email protected] ~]# yum clean all

已加载插件：fastestmirror, langpacks

正在清理软件源： local

Cleaning up everything

[[email protected] ~]# yum makecache 生成元数据

[[email protected] ~]# 

[[email protected] ~]# yum install -y dhcp 

3) 编辑配置文件 

[[email protected] ~]# vim /etc/dhcp/dhcpd.conf 

subnet 192.168.87.0 netmask 255.255.255.0 {

  range 192.168.87.10 192.168.87.100;

  option routers 192.168.87.1;

  option domain-name-servers 114.114.114.114, 8.8.8.8;

}

[[email protected] ~]# systemctl start dhcpd

[[email protected] ~]# systemctl enable dhcpd >>>设置服务开机自动启动

Created symlink from /etc/systemd/system/multi-user.target.wants/dhcpd.service to /usr/lib/systemd/system/dhcpd.service.

[[email protected] ~]# ss -anup | grep :67

UNCONN     0      0            *:67                       *:*                   users:(("dhcpd",pid=1822,fd=7))

UNCONN     0      0      *%virbr0:67                       *:*                   users:(("dnsmasq",pid=1506,fd=3))

4) 测试 

DHCP排错：

日志：/var/log/messages 

# tail -f /var/log/messages 

本文出自 “lyw666” 博客，请务必保留此出处http://lyw666.blog.51cto.com/12823216/1957476