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Where are the passwords of the users located in Linux?

C an you tell me where the passwords of the users located in the Linux operating system?

The /etc/passwd is the password file that stores each user account. The /etc/shadow file stores contain the password hash information for the user account and optional aging information. The /etc/group file is a text file that defines the groups on the system. There is one entry per line.

Tutorial details
Difficulty level	Easy
Root privileges	No
Requirements	Linux
Est. reading time	3 minutes

Where are the passwords of the users located in Linux?

Sample /etc/shadow file on Linux – Click to enlarge

The order is as follows:

1. Username : It is your login name.
2. Password : It is your encrypted password hash. The password should be minimum 8-12 characters long including special characters, digits, lower case alphabetic and more. Usually password format is set to $id$salt$hashed , The $id is the algorithm used On GNU/Linux as follows:
   1. $1$ is MD5
   2. $2a$ is Blowfish
   3. $2y$ is Blowfish
   4. $5$ is SHA-256
   5. $6$ is SHA-512
3. Last password change (lastchanged) : Days since Jan 1, 1970 that password was last changed
4. Minimum : The minimum number of days required between password changes i.e. the number of days left before the user is allowed to change his/her password
5. Maximum : The maximum number of days the password is valid (after that user is forced to change his/her password)
6. Warn : The number of days before password is to expire that user is warned that his/her password must be changed
7. Inactive : The number of days after password expires that account is disabled
8. Expire : days since Jan 1, 1970 that account is disabled i.e. an absolute date specifying when the login may no longer be used.

A password hash is nothing but a string that verifies the integrity of your password during login against the stored hash so that your actual password never has to be held in /etc/shadow file. It is a security feature.

How to view the contents of the /etc/shadow file

The normal user cannot access the /etc/shadow file directly. For example, try out the following cat command:
$ cat /etc/shadow
Sample outputs:

You can only access the /etc/shadow file via few commands such as the passwd command. Login as root user and execute cat command on /etc/shadow file:
$ su —
Provide root user password when prompted:

Try to display the file:
# cat /etc/shadow
Sample outputs:

Here is how my encrypted password hash looks on Linux:

We can use the chage command to get account aging information in easy to understand format:
chage -l vivek
And now I see:

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How To Linux Set or Change User Password

Linux Set User Password

Type following passwd command to change your own password:
$ passwd
Sample Outputs:

The user is first prompted for his/her old password if one is present. This password is then encrypted and compared against the stored password. The user has only one chance to enter the correct password. The super user is permitted to bypass this step so that forgotten passwords may be changed. A new password is tested for complexity. As a general guideline, passwords should consist of 10 to 20 characters including one or more from each of following sets:

1. Lower case alphabetics
2. Upper case alphabetics
3. Digits 0 thru 9
4. Punctuation marks/spacial characters

Linux change password for other user account

You need to login as the root user, type the following command to change password for user vivek:
# passwd vivek
OR
$ sudo passwd vivek
Sample putput:

• vivek – is username or account name.

Passwords do not display to the screen when you enter them. For example:

Linux changing user password using passwd

Linux Change Group Password

When the -g option is used, the password for the named group is changed. In this example, change password for group sales:
# passwd -g sales
The current group password is not prompted for. The -r option is used with the -g option to remove the current password from the named group. This allows group access to all members. The -R option is used with the -g option to restrict the named group for all users.

Changing user passwords on Linux

As a Linux system administrator (sysadmin) you can change password for any users on your server. To change a password on behalf of a user:

1. First sign on or “su” or “sudo” to the “root” account on Linux, run: sudo -i
2. Then type, passwd tom to change a password for tom user
3. The system will prompt you to enter a password twice

To change or set a new root (superuser) password type:
$ sudo passwd

Forcing Linux user to change password at their next login

By default, Linux passwords never expire for users. However, we can force users to change their password the next time they log in via GUI or CLI methods. The syntax is straightforward:
$ sudo passwd -e
$ sudo passwd —expire
Let us immediately expire an account’s password:
$ sudo passwd -e marlena
The system will confirm it:

When user try to login via ssh command, they will see the following on screen:

Locking and Unlocking user password of the named account

Note that the following local command does not disable the account. The user may still be able to login using another authentication token, such as an SSH key. To disable the account, administrators should use either usermod —expiredate 1 or sudo passwd —expire command. Also, users with a locked password are not allowed to change their password to get around the security policy set by sysadmin.

We can lock the password as follows:
$ sudo passwd -l
This option disables a password by changing it to a value which matches no possible encrypted value (it adds a ! at the beginning of the password in the /etc/shadow file. Want to unlock the password, try:
$ sudo passwd -u
The above command option re-enables a password by changing the password back to its previous value. In other words, to the value before using the -l option.

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A note about setting up a secure Linux password

Compromises in password security typically result from careless password selection. Avoid common password such as:

1. Words which appears in a dictionary
2. Your first and last name
3. Pet names
4. Kids or spouses names
5. License number
6. Date of birth (DoB)
7. Home or office address

I strongly recommend that you generate a unique password for all user accounts using your chosen password manager.

Conclusion

The passwd command line utility is used to update or change user’s password. The encrypted password is stored in /etc/shadow file and account information is in /etc/passwd file. To see all user account try grep command or cat command as follows:
$ cat /etc/passwd
$ grep ‘^userNameHere’ /etc/passwd
$ grep ‘^tom’ /etc/passwd
The guidance given in this quick tutorial should work with any Linux distribution, including Alpine, Arch, Ubuntu, Debian, RHEL, Fedora, Oracle CentOS, SUSE/OpenSUSE and other popular Linux distros.

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Where to find password for users created in Ubuntu (16.04)

I’m new to Ubuntu i have made to 2 ordinary users in my Ubuntu and provided them same password but now i want to check is passwords are similar but don’t know where to look for it or what command line to write in terminal. Where to find /etc/password.

1 Answer 1

There are two main files related to system user authentication: /etc/passwd and /etc/shadow . The actual user’s passwords are stored as hashed version in the shadow file. They are hashed by the crypt function. It is not possible to «decrypt» any password from the shadow file, because hashing is one way mechanism.

Most simply: When the user enters а password, it is processed and compared to the hashed password stored in the shadow file. But when one try to «decrypt» a password from the shadow file — there are over than thousands possible results.

/etc/passwd contains one line for each user account, with seven fields delimited by colons ( : ).

These fields are: 1. login name; 2. optional encrypted password; 3. UID; 4. GID; 5. user name or comment field; 6. user home directory; 7. optional user command interpreter.

The encrypted password field may be blank, in which case no password is required. However, some applications which read the /etc/passwd file may decide not to permit any access at all if the password field is blank.

If the password field is a lower-case x , then the encrypted password is actually stored in the shadow file instead; there must be a corresponding line in the /etc/shadow file, or else the user account is invalid. If the password field is any other string, then it will be treated as an encrypted password, as specified by crypt . (source: man passwd )

/etc/shadow — shadowed password file — is a file which contains the password information for the system’s accounts and optional aging information. Each line of this file contains 9 fields, separated by colons ( : ).

The fields are: 1. login name; 2. encrypted password — refer to crypt for details on how this string is interpreted; 3. date of last password change; 4. min password age; 5. max password age; 6. password warning period; 7. password inactivity period; 8. account expiration date; 9. reserved field. (source: man shadow ).

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How to Manage Your User Password from the Terminal in Linux

Like with so many things in the Linux world, passwords are most easily managed directly from the command line. The passwd utility was designed to allow you quick and easy access to all of the password-related commands on your system. You can use it to change and manage your own password as well as the passwords of other users on your system. You can also use it to disable password authentication for a user, lock a user’s account, and set mandatory expiration dates, all to keep your system secure.

Let’s take a look at the passwd utility and how you can use it to manage your password in Linux.

Change Your Password

First, the easiest thing you can do with the passwd utility is change your own password. Just use the passwd command with nothing else.

It’ll ask you to supply your current password followed by your new one.

Change Someone Else’s Password

With root privileges or sudo, you can change someone else’s password, too. Just give passwd the account username for the password you want to change.

This time it won’t ask for their current password. It will only ask for you to set a new one.

Locking a Password

You can just as easily lock a user’s account by locking their password. This will make them unable to sign in using a password. Other methods, like SSH keys, will still work. In order to lock an account, you’ll need sudo and the -l flag.

You can unlock an account, too, with the -u flag.

Locking Root

If, for security reasons, you want to lock all access to the root account, leaving sudo the only way to manage the system, you can do that, too.

It works the same as with any other user.

Using an Empty Password

You can also choose to set a user with an empty password. This is a really bad idea for security, but it can save you a lot of hassle on things like multimedia PCs that you don’t necessarily need to secure that way. Once again, passwd has a simple flag to remove a user’s password, making it blank.

Password Expiration

It’s fairly common to set passwords to expire every so often. It’s a good security measure that prevents stale user passwords from compromising a system. If you’re running a system in a business situation, it’s hard to control what your customers use as their passwords and whether they get compromised. Forcing them to change their password after a set time frame will force your users to keep fresh passwords and reduce the risk of a breach.

Use the -x flag followed by the number of days you want the user’s password to be valid.

That will set the user’s password to expire after thirty days.

You can also set up a system to warn the user that their password will expire soon. Use the -w flag with the amount of days before expiration to automatically warn the user to change their password.

If you know there has already been an issue with a user’s password, you can automatically make their password expire. This will force them to set a new one immediately.

That’s all you really need to get started with passwd. If you’d like to see more of what it can do, check out the utility’s man page.

It’ll tell you everything that you can do with passwd. Passwd is an invaluable tool for Linux administrators. Even if you’re not running a big business server, you can still take advantage of passwd to keep your desktop more secure.

Nick is a freelance tech. journalist, Linux enthusiast, and a long time PC gamer.

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