We all know them:
letmein are all fairly common passwords and are easy to guess. Still, people use them. Would it be a bad idea to not allow users to use common passwords? I could display an error message with a list of "bad passwords that you cannot use."
Should I allow my users to be able to do simple passwords, only warn them, or should I not allow them at all? Some of the passwords above are probably tried with most cracking software first. I'd imagine that most users would be annoyed, but this is the last "flaw" I can see in my software as far as trying to get in without the password. There's always going to be the problem of someone telling something else, it getting written down, reusing passwords, etc. That's inevitable.
Of coarse, hackers could read a list of "banned passwords" and decide to not use those, but that would be harder for a bot to realize that, and I'd imagine that they'd move on unless they're targeting a singe account. Is this a bad idea or is it fine?