I'm curious if anyone has come up with an innovative way to block
someone from submitting a form. I've tried each of these, with limited
success:

1. Block by IP (ie, 192.168.2.1) - works great unless they're on dial-
up or have a dynamic IP.

2. Block by block of IP addresses (ie, 192.168.xx.xx) - horrible idea,
this blocks anyone using a specific ISP. This is only good to block
anonymous IPs.

3. Log computer components (screen resolution, browser, OS, etc), and
block anyone meeting all of those same variables. Not very effective;
too many people use the same default settings, and you don't want to
block all of them. It does work effectively to block international
users, robots, and hackers, though.

4. Set a - this was the most logical; set a boolean field in
the user database, and make this field "true" when you want to block
that user. Then, write the program to set a permanent if this
field is true. The form then checks for this . Works great until
someone figures out the trick.


Any other ideas?