Tuesday, April 1, 2008

How do I disable null passwords?

Resolution:A null password allows users to log onto a system without having to first supply a valid password string. When users have null passwords, they can press the [Enter] key when prompted for a password and gain access to systems without a password. This poses a significant security risk to the system and to the accountability of actions performed by users.

To disable null passwords make a backup of the /etc/pam.d/system-auth file, then modify the original by removing nullok from one of the lines.
Backup /etc/pam.d/system-auth
cp /etc/pam.d/system-auth /etc/pam.d/system-auth.backup
Remove nullok from the following line in /etc/pam.d/system-auth


auth sufficient /lib/security/pam_unix.so likeauth nullok


after removal the line should look like:


auth sufficient /lib/security/pam_unix.so likeauth

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