A network sniffer installed on a computer can read every piece of data sent out from your machine across the network, including passwords. The ease with which a sniffer can find your password ensures that it is one of the first programs a hacker will run on a machine he or she has broken into. They willingly share their passwords. More important, users are too predictable in their choice of passwords. Left to their own devices, users often choose a password that is too short or too easy to guess.
Passwords are about identity.
We tend to reveal ourselves in our passwords. Or we are wise enough to avoid any personal references but choose a word that is ridiculously short, a dictionary word, a name or word spelled backward, or an alphabet or keyboard sequence. Just because we think a foreign word is obscure doesn't mean that it isn't in a dictionary somewhere. The point is that all of these types of words are easily guessed, which makes the job of password cracking straightforward. Some systems have programs that check the password selected and can disallow a poor choice, but not all systems at Duke have this capability.