The primary defense against a brute force attack must be enforcement of a strong password policy. As mentioned earlier, dictionary words make poor passwords. Password size is also important: the longer the password, the more difficult it will be to force. While there is no strict definition of a strong password that will be harder to determine via a dictionary attack, some good guidelines would be:

These guidelines may seem overly strict, but there is little chance that a password created with these restrictions will be found with a brute force attack. There are almost 70 trillion combinations of characters that can be seven digits long and can include upper case characters, lower case characters, numbers, and punctuation. Even a dictionary attack tool that could make one hundred requests per second would still take over 11,000 years before it would be statistically likely to guess the password.