I am getting lot's of those exceptions inside a Rails application:

ActionController::UnknownHttpMethod: CONNECT, accepted HTTP methods are get, head, put, post, delete, and options

So far as I view it appears to become some crawler or something like that like this attempting to use CONNECT being an http verb. I have never heard about it, but the documentation say:

This specs reserves the technique title CONNECT to be used having a proxy that may dynamically change to as being a tunnel (e.g. SSL tunneling [44]).

Any ideas what may be happening? Some poorly written crawler? Something attempting to abuse my application or web server? So what can I actually do about this? Totally block them, if that's the case how? This can be a Ruby on Rails application running with Passenger on Apache.

Are the demands from the same IP or hostname? If that's the case I'd use Apache's mod_authz_host mod_access to deny accessibility, probably, crawler. Since Rails does not appear to do anything using the request I would not be worried about it an excessive amount of though :)