Linux Services DHCP detailed

DHCP-----Dynamic Host Configuration Protocol Protocol

Application Layer Protocol

Role: assigning IP information to clients

Principle:

1. Client sends DHCP discovery to explore DHCP server

2. DHCP server sends DHCP offer (IP/NETMASK/GATEWAY/DNS)

3. Client sends DHCP Request

4. DHCP server sends DHCP ACK

5, the client sends Gratuation ARP to detect whether the IP address conflicts

Software: DHCP

Configuration file:/etc/dhcp/dhcpd.conf

Service: DHCPD

Port: 67/UDP (DHCP server-side port), 68/UDP (DHCP client port)

Example: Configuring a DHCP server

Environment Description:

Isolated Network: Lan1 Network segment: 192.168.87.0/24

DHCP server: 192.168.87.101, dhcpserver.linux.com

Client:

Linux

Windows XP

1) Configure host name, IP address

[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 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) Configure the Yum source to install the DHCP software

[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

Loaded plugins: Fastestmirror, LangPacks

Cleaning up software Source: Local

Cleaning up everything

[[email protected] ~]# yum makecache generate meta data

[Email protected] ~]#

[[email protected] ~]# Yum install-y DHCP

3) Edit the configuration file

[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 >>> set up service boot automatically

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) Testing

DHCP Debug:

LOG:/var/log/messages

# tail-f/var/log/messages

This article is from the "lyw666" blog, make sure to keep this source http://lyw666.blog.51cto.com/12823216/1957476

Linux Services DHCP detailed