MyBB Community Forums

Is there a way to ban and IP address from viewing or registering on my forums?

There is . Go to: admin cp> Board Settings > Change > Banning Options > then scroll down to "Ban by IP" and enter there ip there and click "Submit Changes"

But if the user is on dial up, the next time he reconnects, it will be a different ip so its impossible to block that user forever until IP wildcards (% or *) are implemented in a future version.