Radius, Remote Authentication Dial In User Service is a networking concept which is used to provide access to users to services which require logging in, generally with a username and password. This protocol uses servers to store information in the form of a list of user names or passwords. So, when a user wants to log onto for example, the internet, he enters his user name and password and submits them. The data is sent to the RADIUS server and checked against a list of existing users and their respective passwords. If the username and password entered by the user matches the one on the list, then the user is granted access to the internet.
This protocol is widely used by Internet Service Providers (ISPs) as well as large companies, corporations, educational institutions and other organizations to regulate and manage access to the internet as well as to internal networks. Normally these authentications protocol is carried out by devices like the modem, Digital Subscriber Lines (DSLs) automatically.
The most important functions of the RADIUS server can be summarized as AAA or Authentication, Authorization and Accounting. The first two ‘A’s refer to...