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# User authentication process.
- URL: https://snubmonkey.com/user-authentication-process/
- Published: 2022-02-24T05:17:00.000Z
- Updated: 2025-04-16T22:35:20.000Z
- Author: yannick Coffi
- Tags: security 🦾🦿, linux 🐧, audio  🔊

Have you ever asked yourself how the user authentication process works?  
Let's jump.   
  
### What is User Authentication?

User authentication is a security process that covers all of the human-to-computer interactions that require the user to register and log in.   
Simply said, authentication asks each user: *'who the hell are you?'*  
and verifies their response.  
  
Each user account contains two Unique Identifiers: **Username** and **user identifier** also abbreviated to **user ID** or **UID**.  
When a user account is created, its Username is mapped to a unique UID.   
  
Username is used to access the user account.   
Username is also known as the login name.  
UID is used to authenticate, track and monitor the activity of a user account. Username is used by the user while the UID is used by the system.

That unique ID and key will allow the user to access his/her account.   

### Process

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

**1**\- The System checks whether the user account exists or not.

**2**\- If the user account exists, it checks whether the user is allowed to login from that particular location where username and password are entered or not.

**3**\- If the user is allowed to log in, it checks the supplied password.

**4**\- If the supplied password is incorrect, it checks the threshold value for retries.

**5**\- If the threshold value is exceeded, it locks the account.

**6**\- If the threshold value is not exceeded, it allows the user to retype the correct password.

**7**\- If the supplied password is correct, it checks the password expiry date.

**8**\- If the password is expired, it forces the user to update his/her password.

**9**\- If the password is about to expire, it shows a configured warning message which prompts the user to change his/her password before the expiry date.

**10**\- If the supplied username and password are correct and all the above conditions are satisfied, the user is allowed to log in.

  
...with this, we end this tutorial on what a User authentication process in Linux is.  
Cheers :\~)