Ubuntu DHCP server
From Bjoern Hassler
How to make a dhcp server from an Ubuntu install (say if your router doesn't have dhcp).
Install DHCPD3 via synaptics. Then
sudo nano -w /etc/dhcp3/dhcpd.conf
Amend that file to create a subnet configuration (there's instructions in the file)
at the command line.
Note that the dhcp server itself needs to have a static ip address, which you can set up using the graphical network manager in ubuntu.