Authentication - 9 : Authentication Process
The authentication process is a set of steps that must be followed to allow a user or device to access the network.
The first step is to configure a database with usernames, passwords, and information about which resources are accessible to which people. Why is this step important? Well, just because a user is allowed to access the network, you may not want him or her to have access to the whole network. Configuring the database allows you to control a user's level of access.
The next step is to select an authentication protocol. This protocol is configured on the switch and also on the computer containing the authentication database. Typically RADIUS or LDAP is used for this. RADIUS has the ability to use its own database or any other standards-based accessible database. LDAP also works with most forms of databases.
The next step is to enable both the authentication server and the authentication clients. The clients are just authentication software installed on the switches. Their job is to communicate directly with the end users.
Now we are ready to perform authentication. A user turns on his or her computer, which activates the port on the switch. Once the link is enabled, the computer attempts to communicate with the switch. The switch, upon seeing data from a new port, sends a request to the computer for authentication information. This normally arrives as a request for a username and a password. The user inputs this information and returns it to the switch.
The authentication client in the switch forwards this information to the authentication server for verification.
If approved, the user is allowed access to the network and the specific resources he or she is permitted to access.
If the authentication is disallowed, the switch disables the attached port and alerts the network manager of an unauthorized user attempting to access the network.
As long as the user is connected and active, the link remains up. As soon as the port is disconnected, or the PC is turned off, the authentication process terminates the connection. A new connection must go through the authentication process again.