DHCP configuration for dhcp server Learning

To learn about the content of a DHCP server, we must be clear about its basic concepts and configurations. Let's take a look at DHCP. DHCP is based on the customer/Server mode. When the DHCP Client is started, it automatically communicates with the DHCP server. The DHCP server provides the DHCP client with a service that automatically allocates IP addresses. Of course, advanced DHCP is not just as simple as allocating addresses. Today, we only set up a normal DHCP server for our courses. The client can obtain the necessary network configuration information for accessing the Internet. A server installed with the DHCP service software is called a DHCP server, while a client with the DHCP function enabled is called a DHCP client. a DHCP server provides services for a DHCP Client by means of address lease, it can be either of the following methods: limited lease term or permanent lease. To learn about a DHCP server, you must know how the DHCP server works:

Dhcp discoverdhcp discovery)

Provided by dhcp offerdhcp)

DHCPREQUESTDHCP request)

DHCPACKDHCP confirmation)

The four steps are necessary for the client to obtain the IP address.

When DHCP is provided, the server has allocated an IP address to the client. The IP address assigned to the client in the second part is temporary. After the client obtains the IP address, it will send a DHCP request to lease the address, after receiving the request, the server will officially allocate the address to the client and then send DHCP confirmation to the client. The four steps mainly deal with Multiple DHCP servers in the same network.

Background process: dhcpd

Script:/etc/rc. d/init. d/dhcpd

Port: 67

Required RPM package: dhcp

Related RPM packages:

 
 

  
  
dhcp-devel-3.0.5-7.el5.i386.rpm   
  
  
dhcpv6-0.10-33.el5.i386.rpm   
  
  
dhcpv6_client-0.10-33.el5.i386.rpm  
 
 

Configuration File:/etc/dhcpd. conf

Log:/var/log/xferlog

Let's try again. The network startup method is also called bootpc. The obtained IP address will not be restricted by the server's lease period. It will always work well. We should first install the DHCP server.

1. Download or find the DHCP service installation package from the CD.

Ii. Installation (dhcp * indicates the installation package name ):

 
 

  
  
# rpm -ivh dhcp* 
 
 

3. Configure the DHCP file:

 
 

  
  
Copy/usr/share/doc/dhcp */dhcpd. conf. sample to the/etc directory and change it to dhcpd. conf.
  
  
# Cp/usr/share/doc/dhcp */dhcpd. conf. sample/etc/dhcpd. conf
  
  
Of course, you can also First vi/etc/dhcpd. conf, and then run the following command in the last line mode:
  
  
R/usr/share/doc/dhcp */dhcpd. conf. sample
  
  
In this way, the content of the dhcpd. conf. sample file will be imported.
  
  
Open dhcpd. conf and modify the following items:
  
  
Subnet is followed by the network segment you defined. It must be the same as the IP address of the local machine,
  
  
Each statement ends with a semicolon (;). Do not forget it.
  
  
For example, if my IP address is "192.168.2.11", the following is my configuration file:
  
  
Ddns-update-style interim;
  
  
Ignore client-updates;
  
  
Subnet 192.168.2.0 netmask 255.255.255.0 {
  
  
Option routers 192.168.2.1;
  
  
Option subnet-mask limit 255.0;
  
  
Option nis-domain "domain.org ";
  
  
Option domain-name "domain.org ";
  
  
Option domain-name-servers 192.168.2.1;
  
  
Option time-offset-18000;
  
  
Range dynamic-bootp 192.168.2.100 192.168.2.254
  
  
Default-lease-time 21600;
  
  
Max-lease-time 43200;
  
  
Filename "/pxelinux.0 ";
  
  
Next-server 192.168.2.11;
  
  
Host ns {
  
  
Next-server marvin.redhat.com;
  
  
Hardware ethernet 12: 34: 56: 78: AB: CD;
  
  
Fixed-address 207.175.42.254;
  
  
}
  
  
}
 
 

Iv. Detailed notes:

 
 

  
  
Ddns-update-style interim; # It is required to define the supported DNS dynamic update types.) generally, we set it to disabled,
  
  
# Interim and none both mean to disable
  
  
Allow/ignore client-updates; # allow/ignore clients to update DNS records
  
  
Allow/deny unknown-clients; # Whether to dynamically allocate IP addresses to unknown users
  
  
Allow/deny bootp; # whether to respond to the activation Query
  
  
Allow/deny booting; # whether to respond to user queries
  
  
Subnet 192.168.2.0 netmask 255.255.255.0 {# Set the subnet Declaration
  
  
# --- Default gateway
  
  
Option routers 192.168.2.1; # Set the default gateway to 192.168.2.1
  
  
Option subnet-mask subnet mask 255.255.0; # Set the client subnet mask
  
  
Option nis-domain "domain.org"; # Set the NIS domain for the customer
  
  
Option domain-name "domain.org"; # Set a domain name for the customer
  
  
Option domain-name-servers 192.168.2.1; # Set the domain name Server for the customer
  
  
Option time-offset-18000; # Eastern Standard Time # specify the Greenwich Mean time offset Time for the client, in seconds,
  
  
# This option can be used in both global and local configurations.
  
  
# Option ntp-servers 192.168.2.1; # NTP is a time server
  
  
# Option netbios-name-servers 192.168.2.1; set the wins Server
  
  
# --- Selects point-to-point node (default is hybrid). Don't change this unless
  
  
# -- You understand Netbios very well
  
  
# Option netbios-node-type 2; # setting the netbios node type I don't know what this netbios node is.
  
  
Range dynamic-bootp 192.168.2.28 192.168.2.254; # Set a dynamic address pool
  
  
Default-lease-time 21600; # Set the default address lease period
  
  
Max-lease-time 43200; # set the maximum client address lease period
  
  
# We want the nameserver to appear at a fixed address
  
  
Filename "/pxelinux.0"; # Name of the Startup file, which is applied to diskless installation. It can be the relative or absolute path of tftp.
  
  
Next-server 192.168.2.11; # This is the name of the server they shocould get it from
  
  
# Tftp server, which can be different from the dhcp server. This parameter is generally used by PXE networks.
  
  
# Set host Declaration
  
  
Host ns {
  
  
Next-server marvin.redhat.com;
  
  
Hardware ethernet 12: 34: 56: 78: AB: CD; # specify the mac address of a dhcp Client
  
  
Fixed-address 207.175.42.254; # assign an ip address to the specified mac address
  
  
}
  
  
}
 
 

5. After configuring the dhcpd. conf file, you can start the dhcp service:

# Service dhcpd restart

You can run the "netstat-nlutp" command to check whether the dhcp service has been started.

6. Other related documents:

1. This file/var/lib/dhcpd. leases can view the rented IP address and related information.

2. This file/etc/sysconfig/dhcpd is the network card that the DHCP server listens to. If there is only one network card, you do not need to set DHCPDARGS = eth0 or eth1.

3. This file/etc/sysconfig/dhcrelay is the file for configuring DHCP relay. Open it. Interfaces is the dhcp discover request from this port) will be forwarded to the subsequent DHCPSERVERS server. If DHCP relay is set, you need to start the relay service: service dhcrelay start.

7. Under the linux client, you can manually configure your dhcp:

Check your network configuration file. If you are not set to enable the network automatically, modify the network configuration file.

 
 

  
  
# Vi/etc/sysconfig/network
  
  
Add "NETWORKING = yes" to enable network connection during boot)
  
  
Or use
  
  
# @ Echo "NETWORKING = yes">/etc/sysconfig/network
  
  
Then modify your Nic configuration file.
  
  
The/etc/sysconfig/network-scriptes/ifcfg-eth0 file should contain these lines:
  
  
DEVICE = eth0
  
  
BOOTPROTO = dhcp
  
  
ONBOOT = yes