I know that it is a "bad" idea, I know that it is not secure, I know. I searched the net for an answer and all I saw was whining that it's not good. But I like using Linux because it lets me make the system I want and like to use. The end of intro.

I try to change password:

user:~% passwd
Changing password for user.
(current) UNIX password:
Enter new UNIX password:
Retype new UNIX password:
You must choose a longer password

If I try sudo passwd user then I can set any password I want so I don't need password complexity checks for passwd on my system.

After googling I've found that there should be PAM module pam_cracklib that tests password for complexity and it can be configured. But my PAM password settings doesn't include pam_cracklib:

% cat /etc/pam.d/passwd | grep '^[^#]'
@include common-password
% cat /etc/pam.d/common-password | grep '^[^#]'
password    [success=1 default=ignore]  pam_unix.so obscure sha512
password    requisite           pam_deny.so
password    required            pam_permit.so
password    optional    pam_gnome_keyring.so 

I guess that pam_unix makes this test... Oops... Guys, the moment I finished to write this sentence I've got an enlightenment and typed man pam_unix in terminal where I've found needed options for pam_unix module.

I just removed option obscure and added minlen=1 and now I'm happy. So now I have this line in /etc/pam.d/common-password:

password    [success=1 default=ignore]  pam_unix.so minlen=1 sha512

and I can set any password.

I decided to keep this post for people who might need this solution also.

  • I can't answer my own question for 8 hours after asking, will wait :)
    – wobmene
    Mar 17, 2012 at 11:47
  • 1
    I simply wanted to change my pwd to 123. Couldn't do that with passwd. Tried "sudo passwd <user_name>" and it worked like charm. Didn't need rest of the mumbo-jumbo. Thanks for that part! : )
    – zeFree
    Oct 2, 2013 at 13:22
  • @zeFree, the key point of my solution is allowing any user (not having sudo permissions) to use simple passwords
    – wobmene
    Oct 4, 2013 at 20:29
  • 3
    Great Intro. I have a windows laptop that spends 50% cpu cycles protecting me from viruses. Guess what? Do not need any viruses. The computer is already worthless. So .. linux lets us do what we want. I'm behind a firewall and the computer does not leave my home. Short password? Yes please. Dec 3, 2016 at 6:28
  • 1
    WestCoastProjects used to be correct, Linux used to let us do what we want, which is exactly the problem here. It can feel free to give a warning about using a password that it considers weak and isn't up to its standards, but it shouldn't block us from using one, especially, since Linux users usually know what they're doing. 🤦
    – Synetech
    Jun 12, 2021 at 14:56

7 Answers 7


Ok, I will answer my question :)

I've found that pam_unix module performs password complexity check and it can be configured.

man pam_unix:

       Set a minimum password length of n characters. The default value is
       6. The maximum for DES crypt-based passwords is 8 characters.

       Enable some extra checks on password strength. These checks are
       based on the "obscure" checks in the original shadow package. The
       behavior is similar to the pam_cracklib module, but for
       non-dictionary-based checks.

Alter the line in the pam_unix module in the /etc/pam.d/common-password file to:

password    [success=1 default=ignore]  pam_unix.so minlen=1 sha512

It allows you to set any password with minimal length of 1.

  • 1
    Related details on password complexity: askubuntu.com/questions/244115/… Sep 24, 2019 at 21:31
  • 2
    Bonus hint: remove the obscure option if present.
    – garlix
    Apr 6, 2022 at 9:50
  • Ubuntu 20.20 : after setting min len to 3, I entered new pass. It threw message that min pass length is 8. I typed pass again. It said password set. So ignore warning if you have. It will work
    – amol goel
    Aug 23 at 1:39

If it is a once off, using the passwd command as root you can set a simple password for a user by simply entering the desired value, and then enter the password two times at the prompts.

john@workpad:~$ sudo bash
[sudo] password for john: 
root@workpad:/home/john# passwd john
New password: 
Retype new password: 
passwd: password updated successfully
root@workpad:/home/john# exit
  • 7
    He means doing sudo su && passwd username then Linux will allow you to use any password you would like.
    – user
    Aug 15, 2019 at 1:35
  • 3
    Note that you will still get the warning "BAD PASSWORD", but this lets you change the password anyway.
    – Flimm
    Sep 30, 2022 at 9:40

Open the common-password config file for editing:

sudo -H gedit /etc/pam.d/common-password

Comment this line by adding the # character to the front as shown:

#password   [success=2 default=ignore]  pam_unix.so obscure use_authtok try_first_pass sha512

Also comment this line, otherwise password setting will ask you to pass a mix of upper/lower case letters:

#password   requisite           pam_passwdqc.so enforce=everyone max=18 min=disabled,8,8,1,1 retry=2 similar=deny

Now just add this line into the same file:

password    [success=1 default=ignore]  pam_unix.so minlen=1 sha512

this should do it...

  • FYI, there is no pam_passwdqc.so line in my default install of 14.04 server. Maybe someone (admin?) added it on purpose? ;)
    – Tomofumi
    Aug 29, 2014 at 8:40
  • correct answer for ubuntu 22.04
    – Suhas.s
    Mar 1 at 10:20

For me on Ubuntu 21.04 in /etc/pam.d/common-password file:

  1. Comment this line, because pwquality is an analogue of pam_cracklib for password restrictions

password requisite pam_pwquality.so retry=3

  1. Change next line from

     password    [success=2 default=ignore]  pam_unix.so obscure use_authtok try_first_pass sha512


    password        [success=2 default=ignore]      pam_unix.so minlen=1 sha512

in /etc/pam.d/common-password change this line:

password requisite pam_pwquality.so retry=3


password requisite pam_pwquality.so dictcheck=0 retry=3 

means set dictcheck=0, it will ignore the dictionary check

  • i finished with sudo apt-get purge libpam-pwquality :)
    – zb'
    Dec 1, 2022 at 8:11

I tried ALL of the methods on a machine with a strange and very strict installation using a manipulation resistant PAM.

On this machine, none of the tricks above helped to change the password of a local account (without windows domain) to some new value. The PAM rules always kicked in, even when using sudo passwd

Changes on the /etc/pam.d/common-password resulted in passwd failing alltogether due to 'manipulation error'.

My solution to it was to set the password on another machine on which I also have root access, then copy/paste the hashed value from the /etc/shadow from that machine to the other simply using sudo vi /etc/shadow . The strict PAM did not block that, and it works. (yes, I know it also copies the salt)


for Ubuntu 22.04 LTS

in /etc/pam.d/common-password change this line:

password requisite pam_pwquality.so retry=3


password requisite pam_pwquality.so retry=3 minlen=6

  • There is already an answer that has been accepted. How is yours an improvement? This is an 11 year old question. Many things have changed in Ubuntu in the last 11 years.
    – David
    Apr 4 at 9:33
  • Changing pam_pwquality.so is already mentioned in askubuntu.com/a/1430471/158442
    – muru
    Jul 5 at 10:21

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