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Are there any particular rules on what a valid password is, speaking of length, upper- and lower and/or special characters, numbers, etc. and if so how they can be changed?

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closed as too localized by Luis Alvarado Mar 14 '13 at 16:34

This question is unlikely to help any future visitors; it is only relevant to a small geographic area, a specific moment in time, or an extraordinarily narrow situation that is not generally applicable to the worldwide audience of the internet. For help making this question more broadly applicable, visit the help center.If this question can be reworded to fit the rules in the help center, please edit the question.

Do you think you could rephrase your question? I've read it a few times, but I still don't quite understand what it is you're asking. – Tommy Brunn Aug 7 '10 at 12:33
I think the question is if there are any rules what a valid password is, and if so how they can be changed. I agree the question should be rephrased. – txwikinger Aug 7 '10 at 15:14
Correct, fixing it. – Mashimom Aug 9 '10 at 12:30

Password strength rules are defined in the pam configuration in /etc/pam.d/, usually using the pam_cracklib module. However, the minimmum password length of 6 is hardcoded in the pam_unix module.

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I'm not entirely sure of your question, but it sounds like you're asking about passwords not being changed when you change the user account password - I'm assuming you mean external passwords in things like mysql?

From what I understand, the user account password only changes the password used to login to Ubuntu (and the sudo password for your account).

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