Each ordinary user account should have a unique user-id number, typically in the range of 100 to 30,000. I have seen systems where everyone logged into an account bearing a unique user name, but everyone shared the same user-id. Even the home directory was the same. The system administrator might just as well have had a single user account as far as accountability goes. Listing 1B shows some sample output.
Any program executing with user-id zero has unlimited access to any file or program on the system.
The root account is generally the only legitimate account with this access privilege. Instead, the password will be stored in the alternate password file, whose permissions are adjusted so only the superuser can read it. Listing 1C shows what a password file looks like when used in conjunction with the passwd.adjunct file. Even though such passwords can't be unencrypted by any known algorithm, they can be guessed. Password cracking software uses one or more dictionaries or other lists to provide words used for guesses.