linux服務DHCP詳解

DHCP -----   Dynamic Host Configuration Protocol   動態主機配置協議

應用層協議

做用：爲客戶端分配IP信息 

原理：

一、客戶端發送DHCP Discovery探索DHCP服務器 

二、DHCP服務器發送DHCP Offer (IP/NETMASK/GATEWAY/DNS)

三、客戶端發送DHCP Request

四、DHCP服務器發送DHCP ACK

五、客戶端發送Gratuation ARP用於檢測IP地址是否衝突 

軟件：dhcp

配置文件：/etc/dhcp/dhcpd.conf

服務：dhcpd

端口：67/udp(DHCP服務端端口) , 68/udp(DHCP客戶端端口) 

示例：配置DHCP服務器 

環境描述：

隔離網絡： Lan1     網段：192.168.87.0/24

DHCP服務器：   192.168.87.101, dhcpserver.linux.com 

客戶端：

Linux

windows XP 

1) 配置主機名，IP地址

[root@server ~]# hostnamectl set-hostname server.linux.com 

[root@server ~]# 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

[root@server ~]# systemctl restart network

[root@server ~]# systemctl restart NetworkManager

[root@server ~]# 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，安裝DHCP軟件  

[root@server ~]# mkdir /etc/yum.repos.d/default

[root@server ~]# mv /etc/yum.repos.d/CentOS-* /etc/yum.repos.d/default

[root@server ~]# vim /etc/yum.repos.d/local.repo

[local]

name=localsrc

baseurl=file:///mnt

enabled=1

gpgcheck=0

[root@server ~]# mount /dev/cdrom /mnt/

[root@server ~]# yum clean all

已加載插件：fastestmirror, langpacks

正在清理軟件源： local

Cleaning up everything

[root@server ~]# yum makecache 生成元數據

[root@server ~]# 

[root@server ~]# yum install -y dhcp 

3) 編輯配置文件 

[root@server ~]# 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;

}

[root@server ~]# systemctl start dhcpd

[root@server ~]# systemctl enable dhcpd >>>設置服務開機自動啓動

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

[root@server ~]# 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) 測試 

DHCP排錯：

日誌：/var/log/messages 

# tail -f /var/log/messages