Write short notes on User management systems and user authentication process. 

User management systems

There are two ways to manage the user accounts; centralized and standalone.

Centralized user management

In centralized management, user accounts of all systems are managed in a centralized server system. In server system, a directory service such as LDAP (Lightweight Directory Access Protocol) and ADS ( Advanced Design System ) is used for user management and authentication.

In this model, the local system sends the user's login information to the server system. Based on the information stored in the directory service, server system authenticates whether the user is allowed to login or not.

Standalone management

In standalone management, users' accounts are managed in local system. To store users' accounts detail, text files are used.In this model, depending on the locally stored login information, the local system itself authenticates that the user is allowed to login or not.

User authentication process

When a user enters username and password, depending on type of user management model is used, following steps are performed in local system or in remote system.

If centralized model is used, following steps are performed in centralized system through directory service otherwise same steps are performed in local system through those text files which contain user login details.

• System checks whether the user account exists or not.
• If user account exists, it checks whether the user is allowed to login from that particular location where username and password are entered or not.
• If user is allowed to login, it checks the supplied password.
• If supplied password is incorrect, it checks the threshold value for retries.
  • If threshold value is exceeded, it locks the account.
  • If threshold value is not exceeded, it allows user to retype the correct password.
• If supplied password is correct, it checks the password expiry date.
  • If password is expired, it forces user to update his password.
  • If password is about to expire, it shows a configured warning message which prompts user to change his password before expiry date.

If supplied username and password are correct and all above conditions are satisfied, user is allowed to login.