How To Change a User’s Password Using usermod Command in Ubuntu

In this article, we will delve into the process of changing a user’s password using the usermod command in Ubuntu. This command is a powerful tool that allows you to modify a user’s settings, including their password. However, it’s important to note that using usermod to change passwords requires the password to be in an encrypted format.

Understanding the usermod Command

The usermod command in Ubuntu is a user account modification tool. It’s used to change various user account settings, including user’s home directory, shell, password, and others. The syntax for the usermod command is as follows:

usermod [options] LOGIN

In this article, we will focus on the -p option, which allows you to set the user’s password. However, this option requires the password to be in an encrypted format.

Changing User Password with usermod

Using openssl passwd

Firstly, you can use the openssl passwd command to generate an encrypted password. Here’s how:

1. Open your terminal.
2. Type openssl passwd and hit Enter.
3. You will be prompted to enter the password you want to encrypt. After entering it, the terminal will output the encrypted version of your password.

Example:

$ openssl passwd
Password: 
Verifying - Password: 
$apr1$ZzZzZzZz$abcdefgh1234567890abcdef.

Now, you can use this encrypted password with the usermod command:

usermod -p '$apr1$ZzZzZzZz$abcdefgh1234567890abcdef.' username

Replace username with the actual username for which you want to change the password.

Using crypt() hashed password

Another method is to use a crypt() hashed password. You can generate a hashed password using a script or command like Perl:

SALT="Q9"
PLAINTEXT="secret_password"
HASH=$(perl -e "print crypt('${PLAINTEXT}','${SALT}')")

In this script, SALT is a two-character string that will be used to generate the hash, and PLAINTEXT is the password you want to hash. The crypt() function will return the hashed password.

Then, use the usermod command with the hashed password:

usermod -p ${HASH} username

Using mkpasswd and usermod

If mkpasswd is not available on your system, you can install it by installing the whois package:

apt install whois

Then, generate the encrypted password using the mkpasswd command:

mkpasswd -m sha-512 your-secret-password

Finally, use the usermod command with the encrypted password:

usermod -p 'encrypted-password' username

Using passwd Command

While the usermod command can change a user’s password, it’s generally safer and more straightforward to use the passwd command. This command changes the password interactively, prompting you to enter and confirm the new password:

sudo passwd username

Conclusion

In this article, we explored various ways to change a user’s password using the usermod command in Ubuntu. While this command is powerful and flexible, it’s important to remember that it requires passwords to be in an encrypted format. For most users, the passwd command offers a simpler and safer way to change passwords.