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).