Preventing Brute Force Logins on Websites

Question

As a response to the recent Twitter hijackings and Jeff\'s post on Dictionary Attacks, what is the best way to secure your website against brute force login attacks?

Answer 1

A lot of online message boards that I log into online give me 5 attempts at logging into an account, after those 5 attempts the account is locked for an hour or fifteen minutes. It may not be pretty, but this would certainly slow down a dictionary attack on one account. Now nothing is stopping a dictionary attack against multiple accounts at the same time. Ie try 5 times, switch to a different account, try another 5 times, then circle back. But it sure does slow down the attack.

The best defense against a dictionary attack is to make sure the passwords are not in a dictionary!!! Basically set up some sort of password policy that checks a dictionary against the letters and requires a number or symbol in the password. This is probably the best defense against a dictionary attack.