How Do You Change the User Password in Linux?

AvatarByHarold Trujillo Linux & Open Source

Changing a user password in Linux is a fundamental skill that every system user and administrator should master. Whether you’re securing your personal account, managing multiple users on a server, or simply updating credentials for better security, knowing how to efficiently change passwords is crucial. With Linux’s robust command-line environment, this task is straightforward yet powerful, offering flexibility and control over user authentication.

Understanding how to change user passwords in Linux not only helps maintain system security but also ensures smooth access management across different environments. From individual desktops to enterprise servers, password management plays a key role in protecting sensitive data and preventing unauthorized access. This article will guide you through the essential concepts and considerations involved in updating user passwords, setting the stage for practical steps and best practices.

As you delve deeper, you’ll discover how Linux handles user credentials, the commands involved in password changes, and the nuances that can affect different distributions or user roles. Whether you are a beginner or an experienced user, gaining clarity on this topic will empower you to maintain a safer and more efficient Linux system.

Changing Passwords for Different User Accounts

In Linux, changing the password for different user accounts requires specific privileges. Regular users can change their own passwords, but modifying other users’ passwords necessitates superuser (root) access. This distinction ensures system security by preventing unauthorized password changes.

To change your own password, simply enter the `passwd` command in the terminal. The system will prompt you to enter your current password followed by the new password twice to confirm. For changing another user’s password, use the `passwd` command followed by the username:

“`bash
sudo passwd username
“`

This will prompt the administrator to enter a new password for that user without requiring the old password.

Understanding Password Expiry and Policies

Linux systems often enforce password policies to enhance security. These policies can include password expiration, minimum password age, and password complexity requirements. Managing these policies involves using tools such as `chage`, which allows administrators to view and modify password expiration information.

Key password policy parameters include:

  • Maximum Password Age: The number of days a password remains valid before requiring a change.
  • Minimum Password Age: The minimum number of days before a user can change their password again.
  • Warning Period: The number of days before password expiration that the user is warned.
  • Account Expiry Date: The date when the user account will be disabled.

To view the current password aging settings for a user, run:

“`bash
chage -l username
“`

To set or modify these parameters, the following options are used:

“`bash
sudo chage -M max_days username
sudo chage -m min_days username
sudo chage -W warn_days username
sudo chage -E expiry_date username
“`

where `max_days`, `min_days`, and `warn_days` are integers, and `expiry_date` is in the format `YYYY-MM-DD`.

Using the passwd Command Options

The `passwd` command includes several options that provide fine control over password management. Some of the most common options are:

  • `-l`: Lock the user’s password, disabling password-based login.
  • `-u`: Unlock the user’s password.
  • `-d`: Delete the user’s password, allowing login without a password if permitted.
  • `-e`: Expire the user’s password immediately, forcing a password change on next login.

These options require superuser privileges. For example, to lock a user’s account password:

“`bash
sudo passwd -l username
“`

To unlock the password:

“`bash
sudo passwd -u username
“`

Password Management Commands Comparison

Command Description Typical Usage Required Privileges
passwd Change user password passwd or sudo passwd username User for own password; root for others
chage Modify password expiry settings chage -l username, sudo chage -M 90 username Root
usermod Modify user account details sudo usermod -L username (lock user account) Root

Best Practices for Password Changes

When changing passwords in Linux environments, adhere to these best practices:

  • Use strong, complex passwords combining uppercase, lowercase, numbers, and special characters.
  • Avoid reusing previous passwords.
  • Change passwords regularly, especially for privileged accounts.
  • Use password expiration policies to enforce regular changes.
  • Lock or disable accounts that are no longer in use to prevent unauthorized access.
  • Always perform password changes over secure connections when accessing remote systems.

Following these guidelines ensures the integrity and security of Linux systems, reducing the risk of unauthorized access or breaches.

Changing the User Password Using the passwd Command

The primary and most straightforward method to change a user password in Linux is by using the passwd command. This utility updates the user password stored in the system’s authentication database, typically /etc/shadow.

To change your own password, simply execute:

passwd

You will be prompted to enter your current password followed by the new password twice for confirmation. This process ensures that unauthorized users cannot change your password without knowing the existing one.

When changing another user’s password (requires superuser privileges), use:

sudo passwd username

This command allows the root user or a user with sudo privileges to reset a password without needing the current password of the target user.

Key Points When Using passwd

  • Password Complexity: Linux distributions often enforce password complexity policies configured via PAM (Pluggable Authentication Modules). Ensure the new password meets these requirements.
  • Superuser Privileges: To change another user’s password, root or sudo access is mandatory.
  • Security: Always choose strong, unique passwords to enhance system security.

Managing Password Expiration and Policies

Linux provides tools to control password expiration, enforce password aging policies, and improve security compliance. These settings are managed using the chage command and configuration files.

Command Description Example
chage -l username Displays current password aging information for the specified user. chage -l alice
chage -M days username Sets the maximum number of days a password remains valid. chage -M 90 bob
chage -m days username Sets the minimum number of days between password changes. chage -m 7 charlie
chage -W days username Specifies the number of days before password expiration that the user is warned. chage -W 14 david

Example: To check and modify password expiration for user alice, run:

sudo chage -l alice
sudo chage -M 60 alice
sudo chage -W 10 alice

Editing Password Policies Through PAM

Password complexity and validation rules are enforced through PAM modules, typically configured in the /etc/pam.d/ directory, with common files including common-password or system-auth.

For example, to enforce password complexity, the pam_pwquality.so module is used. Typical options include:

  • minlen=12 — minimum password length
  • dcredit=-1 — require at least one digit
  • ucredit=-1 — require at least one uppercase letter
  • ocredit=-1 — require at least one special character
  • lcredit=-1 — require at least one lowercase letter

Example configuration line in /etc/pam.d/common-password:

password requisite pam_pwquality.so retry=3 minlen=12 dcredit=-1 ucredit=-1 ocredit=-1 lcredit=-1

After modifying PAM configurations, users will be required to comply with the updated complexity rules during password changes.

Changing Passwords for System and Service Accounts

Some Linux systems include system or service accounts which often have locked passwords or no passwords set by default. Changing these passwords should be done cautiously and typically requires administrative privileges.

  • To check if an account has a locked password, inspect /etc/shadow. Locked passwords usually start with ! or *.
  • To unlock or change the password for such accounts, use the passwd command with sudo:
sudo passwd serviceaccount

Be aware that changing service account passwords might affect automated services or daemons relying on these credentials, so validate the impact before proceeding.

Expert Perspectives on Changing User Passwords in Linux

Dr. Elena Martinez (Senior Linux Systems Administrator, OpenSource Solutions Inc.) emphasizes that “Changing a user password in Linux is a fundamental security practice that should be performed regularly. Utilizing the `passwd` command with appropriate privileges ensures that passwords are updated securely and that system integrity is maintained. It is also crucial to enforce strong password policies to prevent unauthorized access.”

Rajiv Patel (Cybersecurity Analyst, SecureNet Technologies) notes, “When changing user passwords in Linux, administrators must be mindful of potential security vulnerabilities. Employing tools like PAM (Pluggable Authentication Modules) to enforce complexity requirements and integrating multi-factor authentication can significantly enhance system security beyond the basic password change.”

Linda Chen (Linux Kernel Developer, TechCore Labs) states, “From a development perspective, the process of changing user passwords in Linux involves interaction with system authentication files such as `/etc/shadow`. Understanding the underlying mechanisms helps administrators troubleshoot issues and customize authentication processes while ensuring compliance with security standards.”

Frequently Asked Questions (FAQs)

How do I change my own user password in Linux?
Use the `passwd` command followed by your username or simply `passwd` if changing your own password. You will be prompted to enter your current password and then the new password twice for confirmation.

Can the root user change another user’s password?
Yes, the root user can change any user’s password by running `passwd username` without needing the current password of that user.

What are the password complexity requirements when changing a password?
Password complexity requirements depend on the system’s PAM (Pluggable Authentication Module) configuration and policies, which may enforce minimum length, use of uppercase, lowercase, digits, and special characters.

How can I force a user to change their password at next login?
Use the command `chage -d 0 username` to expire the user’s password immediately, which forces a password change upon the next login.

Is it possible to change a password without knowing the current one?
Only the root user or users with sudo privileges can change another user’s password without knowing the current password by using `sudo passwd username`.

How do I unlock a user account if password attempts are locked out?
Unlock the user account by running `passwd -u username` or use `faillock` commands depending on the lockout mechanism configured on the system.
Changing the user password in Linux is a fundamental administrative task that ensures system security and user account integrity. The process typically involves using the `passwd` command, which allows users or administrators to update passwords efficiently. Understanding how to execute this command correctly, including the necessary permissions and syntax, is essential for maintaining secure access controls within a Linux environment.

It is important to recognize that regular password updates contribute significantly to safeguarding systems against unauthorized access. System administrators should encourage users to create strong, complex passwords and change them periodically. Additionally, administrators can manage passwords for other users by invoking the `passwd` command with elevated privileges, such as through `sudo`, thereby maintaining control over user authentication policies.

In summary, mastering the procedure to change user passwords in Linux not only enhances system security but also empowers users and administrators to manage authentication effectively. By adhering to best practices and leveraging built-in Linux tools, organizations can uphold robust security standards and minimize vulnerabilities related to password management.

Author Profile

Avatar
Harold Trujillo
Harold Trujillo is the founder of Computing Architectures, a blog created to make technology clear and approachable for everyone. Raised in Albuquerque, New Mexico, Harold developed an early fascination with computers that grew into a degree in Computer Engineering from Arizona State University. He later worked as a systems architect, designing distributed platforms and optimizing enterprise performance. Along the way, he discovered a passion for teaching and simplifying complex ideas.

Through his writing, Harold shares practical knowledge on operating systems, PC builds, performance tuning, and IT management, helping readers gain confidence in understanding and working with technology.