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.