FreeRADIUS Server (Radius protocol server)

The FreeRADIUS Server is a daemon for unix and unix like operating systems 
which allows one to set up a radius protocol server, which can be used for 
Authentication and Accounting various types of network access.  To use the 
server, you also need a correctly setup client which will talk to it, 
including terminal servers, Ethernet Switches, Wireless Access Points or a 
PC with appropriate software which emulates it (PortSlave, radiusclient etc).