The Ask: CentOS/RHEL 5,6 systems needs to be configured to use /etc/passwd to store passwords instead of using /etc/shadow.
The steps for making authentication work without /etc/shadow are as follows:
1. Boot into single user mode.
2. Edit /etc/sysconfig/authconfig changing:
3. If this directive is not present then add it. Edit the following line in both /etc/pam.d/system-auth and /etc/pam.d/password-auth:
password sufficient pam_unix.so sha512 shadow try_first_pass remember=24 use_authtok
4. Remove the word shadow:
password sufficient pam_unix.so sha512 try_first_pass remember=24 use_authtok
5. Run the following to convert the current shadow file to a passwd file.