8.2. DHCP Server Setup for Linux

8.2.1. Options for DHCPD

Now you need to configure DHCPd. In order to do this, you will have to create or edit /etc/dhcpd.conf. There is a graphical interface for dhcpd configuration under linuxconf. This makes configuring and managing DHCPD extremely simple.

If you want to configure it by hand, you should follow instructions below. I suggest configuring it by hand at least once. It will help in the diagnostics that a GUI can't provide. Unfortunately Micrsoft doesn't believe this!

The simplest way to assign IP addresses is to assign them randomly. A sample configuration file that shows this type of setup is displayed below:

# Sample /etc/dhcpd.conf # (add your comments here) default-lease-time 1200; max-lease-time 9200; option subnet-mask 255.255.255.0; option broadcast-address 192.168.1.255; option routers 192.168.1.254; option domain-name-servers 192.168.1.1, 192.168.1.2; option domain-name "mydomain.org"; subnet 192.168.1.0 netmask 255.255.255.0 { range 192.168.1.10 192.168.1.100; range 192.168.1.150 192.168.1.200; }

This will allow the DHCP server to assign the client an IP address from the range 192.168.1.10-192.168.1.100 or 192.168.1.150-192.168.1.200.

If the client doesn't request a longer time frame, then the DHCP server will lease an IP address for 1200 seconds. Otherwise, the maximum (allowed) lease the server will allow is 9200 seconds. The server sends the following parameters to the client:

Use 255.255.255.0 as your subnet mask Use 192.168.1.255 as your broadcast address Use 192.168.1.254 as your default gateway USE 192.168.1.1 and 192.168.1.2 as your DNS servers.

If you specify a WINS server for your Windows clients, you need to include the following option in the dhcpd.conf file:

option netbios-name-servers 192.168.1.1;

You can also assign specific IP addresses based on the clients' ethernet MAC address as follows:

host haagen { hardware ethernet 08:00:2b:4c:59:23; fixed-address 192.168.1.222; }

This will assign IP address 192.168.1.222 to a client with the ethernet MAC address of 08:00:2b:4c:59:23.

8.2.2. Starting the server

In most cases the DHCP installation doesn't create a "dhcpd.leases" file. Before you start the server, you must create an empty file:

touch /var/state/dhcp/dhcpd.leases

To start the DHCP server, simply type (or include in the bootup scripts):

/usr/sbin/dhcpd

This will start dhcpd on eth0 device. If you need to start it on another device, simply supply it on the command line as shown below:

/usr/sbin/dhcpd eth1

If you wish to test the configuration for any oddities, you can start dhcpd with the debugging mode. Typing the command below will allow you to see exactly what is going on with the server.

/usr/sbin/dhcpd -d -f

Boot up a client.Take a look at the console of the server. You will see a number of debugging messages appear on the screen.

Your done