Common sense in choosing and protecting passwords can prevent many hacker penetrations to Fermilab computers. For example:
Don't make your password easy to guessónot the same as the username; not personal information, even backwards; not dictionary words; and especially not no password.
Use at least six alphanumeric characters. Passphrases are fine, especially if deliberatly misspeled, but remember most UNIX systems only use the first eight characters.
Don't put passwords in files.
Change your password frequentlyóat least twice annuallyóand donít change it back to a previously used password.
Don't give your password to someone else. If you find that someone knows it, change it immediately.