Support for shadow passwords has been enhanced significantly for Red Hat Linux 6.0. Shadow passwords are a method of improving system security by moving the encrypted passwords (normally found in /etc/passwd) to another file with more restrictive file access permissions. During the installation, you were given the option of setting up shadow password protection on your system.

The shadow-utils package contains a number of utilities that support:

• Conversion from normal to shadowed passwords and back (pwconv, pwunconv).

• Verification of the password, group, and associated shadow files (pwck,
  grpck).

• Industry-standard methods of adding, deleting and modifying user accounts (useradd,
  usermod, and userdel).

• Industry-standard methods of adding, deleting, and modifying user groups (groupadd,
  groupmod, and groupdel).

• Industry-standard method of administering the /etc/group file (gpasswd).

Please Note: There are a few additional points of interest concerning these utilities: