Enable simple password for root user on CentOS
vi /etc/pam.d/system-auth
as root.Look for the following two lines:
password requisite pam_cracklib.so try_first_pass retry=3 password sufficient pam_unix.so md5 shadow nullok try_first_pass use_authtok
Comment out the first of the two lines:
#password requisite pam_cracklib.so try_first_pass retry=3
Remove use_authtok on the second line. Otherwise you’ll get “passwd: Authentication information cannot be recovered” error.
password sufficient pam_unix.so md5 shadow nullok try_first_pass
That’s it. Try changing your password again.