Sometimes it’s annoying when Photon OS based appliances doesn’t allow to use previously used password for root user. You may see the error ‘Password has been already used. Choose another‘ when you try to use the password which was used earlier.
root@test [ ~ ]# passwd New password: Retype new password: Password has been already used. Choose another.
By default, Photon OS remember last Five passwords. You can see the setting ‘remember=3’ in /etc/pam.d/system-password
root@test [ ~ ]# cat /etc/pam.d/system-password # Begin /etc/pam.d/system-password password requisite pam_cracklib.so minlen=8 minclass=4 difok=4 maxsequence=0 retry=3 enforce_for_root password requisite pam_pwhistory.so retry=3 remember=5 enforce_for_root password required pam_unix.so sha512 shadow use_authtok # End /etc/pam.d/system-password
By changing ‘remember ‘ from 5 to 0 we can disable the remember password count and reset the root password.