configuring DHCP server

http://www.linuxhomenetworking.com/wiki/index.php/Quick_HOWTO_:_Ch08_:_Configuring_the_DHCP_Server

dhcpd.conf File

You can define your server configuration parameters in the dhcpd.conf file which may be located in the /etc the /etc/dhcpd or /etc/dhcp3 directories depending on your version of Linux.

Note: The skeleton dhcp.conf file that is created when you install the package may vary in its completeness. In Ubuntu / Debian, the skeleton dhcpd.conf file is extensive with most of the commands deactivated with a # sign at the beginning. In Fedora / RedHat / CentOS an extensive sample is also created with activated commands. It is found in the following location which you can always use as a guide.

/usr/share/doc/dhcp*/dhcpd.conf.sample

Note: The dhcpd.conf configuration file formats in Debian / Ubuntu and Redhat / Fedora are identical.

Here is a quick explanation of the dhcpd.conf file: Most importantly, there must be a subnet section for each interface on your Linux box.

ddns-update-style interim
ignore client-updates
 
subnet 192.168.1.0 netmask 255.255.255.0 {
 
   # The range of IP addresses the server
   # will issue to DHCP enabled PC clients
   # booting up on the network
 
   range 192.168.1.201 192.168.1.220;
 
   # Set the amount of time in seconds that
   # a client may keep the IP address

  default-lease-time 86400;
  max-lease-time 86400;
 
   # Set the default gateway to be used by
   # the PC clients
 
   option routers 192.168.1.1;
   # Don't forward DHCP requests from this
   # NIC interface to any other NIC
   # interfaces
 
   option ip-forwarding off;
 
   # Set the broadcast address and subnet mask
   # to be used by the DHCP clients
 
  option broadcast-address 192.168.1.255;
  option subnet-mask 255.255.255.0;
  
   # Set the NTP server to be used by the
   # DHCP clients

  option ntp-servers 192.168.1.100;

   # Set the DNS server to be used by the
   # DHCP clients

  option domain-name-servers 192.168.1.100;
 
   # 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 192.168.1.100;
 
   # You can also assign specific IP addresses based on the clients'
   # ethernet MAC address as follows (Host's name is "laser-printer":

  host laser-printer {
      hardware ethernet 08:00:2b:4c:59:23;
     fixed-address 192.168.1.222;
   }
}
#
# List an unused interface here
#
subnet 192.168.2.0 netmask 255.255.255.0 {
}