password characteristic
 

How to set the password characteristic such as
i. password aging (minimum and maximum).
ii. Password character (alphanumeric).
iii. Password length.
iv. New password must not the same with previous password.

I trying in linux with
'passwd -n 2 -x 5 testuser'
With this command it seems that i can't change the password for 2 days, But it's failed.

You can add constraints with PAM. One tool that is helpful for testing password requirement strength is cracklib. Check out some of the following links.

http://www.fifi.org/doc/cracklib2/
http://www.debian.org/doc/manuals/se....en.html#s4.10