Proxy Question

Is there a way to detect if site is being accessed via proxy server?

 

I know not a cake specific question but hoping someone might know.

 

Something like this in AppController beforeFilter:

 

                $request_from = $this->request->domain($tldLength = 1);

 

                                if ($request_from != 'my_domain.com') {

                                                $this->Session->destroy();

                                                //$this->Controller->redirect(null, 403, true);

                }

 

Thanks all

 

Dave