How to change a user password on a Linux server

While working on a Linux server, you may need to change the password for a user, including the root user. This guide will provide step-by-step instructions on how to achieve that.

Key Points to Consider:

This guide is applicable to any user on the server, not just the root account.
Ensure you have root access or sudo privileges to change the password.

Step-by-step instructions

Step 1: Log in to your server

Access your server using SSH from your terminal. Use the command below to connect:
```
$ ssh your_username@your_server_ip
```
- Replace your_username with your actual username.
- Replace your_server_ip with the server's IP address.

Step 2: Verify Root or Sudo privileges

Ensure you have root privileges by using the following command:
```
$ sudo -i
```

Step 3: Change the user password

Run the passwd command to change the password for a specific user. Replace username with the target user:
```
$ sudo passwd username
```
- Enter the new password twice when prompted (see Fig. 1).
Fig. 1. Terminal prompt to enter and confirm the new password.

Step 4: Verify password change

After successfully updating the password, you should see a confirmation message (see Fig. 2):
```
passwd: password updated successfully / passwd: all authentication tokens updated successfully
```
Fig. 2. Output confirming that all authentication tokens have been successfully updated.

Quick tip: Generate secure passwords using `pwgen`

pwgen is a handy utility to generate strong, random passwords on Linux. Here are some useful options you can use with pwgen to create highly secure passwords:

Step 1: Install `pwgen`

If pwgen is not already installed, you can install it with:

$ sudo apt install pwgen

Step 2: Use `pwgen` to generate passwords

Here are some common options you can use with pwgen to enhance password security:

Basic password generation:
```
$ pwgen 16 1
```
This generates a 16-character password. You can adjust the number 16 for a different length, and 1 specifies how many passwords to generate.
Secure passwords (with -s):
```
$ pwgen -s 16 1
```
This forces the password to be more random and secure, ideal for critical accounts.
Include symbols (with -y):
```
$ pwgen -sy 16 1
```
This creates a secure password of 16 characters with symbols included.
Avoid ambiguous characters (with -B):
```
$ pwgen -B 16 1
```
This generates passwords that avoids characters that could be mistaken for each other (like O and 0).
Force numeric digits in the password (with -n):
```
$ pwgen -n 16 1
```
This ensures numeric digits are included.

Summary of common `pwgen` options:

-s: Stronger, more random passwords.
-y: Include symbols in the password.
-B: Avoid ambiguous characters.
-n: Ensure the password includes numeric digits.

Summary

In this guide, we outlined how to change the password for any user on a Linux server using the passwd command. Additionally, we explored using the pwgen utility to generate secure passwords, along with several useful options (-s, -y, -B, -n) to customize the complexity and security of your passwords.

Using these steps and tips will help ensure your server is secured with strong and unique passwords for each user.