Getting the Dynamic Host Configuration Protocol (DHCP) server running

DHCP uses TFTP (I think) so it needs to be run on the TFTP server and the TFTP server needs to be running first. Before DHCP can be run the /etc/dhcpd.conf needs to be created. This can be done to a degree through YaST, but to put in all the options it problem needs to be created through a text editor, like emacs (you'll need whole path, which is /opt/gnu/bin/emacs, if you're root). Not sure if I've done this properly, my dhcpd.conf at time of writing is given below

option subnet-mask 255.255.252.0;
option broadcast-address 134.225.100.0;
option domain-name "reading.ac.uk";
option domain-name-servers 134.225.32.11, 134.225.32.12;
option routers 134.225.100.254;
allow booting;
allow bootp;
default-lease-time 14400;
ddns-update-style none;
# Group the PXE bootable hosts together
group {
  option root-path "/tftpboot/";
            	# PXE-specific configuration directives...
  next-server 134.225.100.178;
  filename "pxelinux.0";
            	# You need an entry like this for every host
	# unless you're using dynamic addresses
  host lapse {
    option host-name "lapse";
    hardware ethernet 00:30:48:21:b8:b3;
    fixed-address 134.225.100.13;
  }
}
subnet 134.225.100.0 netmask 255.255.252.0 {
  default-lease-time 14400;
  max-lease-time 172800;
}

I got most of the information for the file above at http://syslinux.zytor.com/pxe.php. Explanation of file:

• Top 5 lines: not sure if this is right (probably only matters if we try and send information outside the local area network), I've used the standard address stuff we use for department machines, where the servers and router are CSC machines (vids1.rdg.ac.uk is 134.225.32.11, vids2.rdg.ac.uk is 134.225.32.12 and gw-100.disk-Ink.rdg.ac.uk is 134.225.100.254).
• allow booting: directs DHCP server to respond to queries from particular clients.
• allow bootp: directs DHCP server to respond to bootp queries.
• next 2 lines: not sure, I don't think they're that important
• tftp lines: option root-path specifies the tftp boot directory; next-server needs to be the TFTP server (in this case ellesmere, 134.225.100.178) and need to specify the name of the network bootstrap program (NBP) which is pxelinux.0.
• host stuff: need to add the MAC address and ip address for the remote nodes we wish to carry out a PXE boot here.
• final lines: not sure what the subnet stuff is at end - probably written by YaST when starting DHCP server, because I don't remember doing it.

Having created the dhcpd.conf file, call up yast2 dhcp-server and select "Start DHCP Server Now".