The connection for the request being processed

The HTTP request being processed

The response for the request being processed

The `HttpRuntime` for the request being processed

The user state for the request being processed

Get the IP of the client from the `HttpContext`.

 Warning; if you don't write these headers in your rev.proxy, the client will
 be able to spoof them. Related headers:
 - client-ip
 - x-forwarded-for: the "X-Forwarded-For" client request header field with
   the $remote_addr variable appended to it, separated by a comma. If the
   "X-Forwarded-For" field is not present in the client request header, the
   $proxy_add_x_forwarded_for variable is equal to the $remote_addr variable.
   from http://nginx.org/en/docs/http/ngx_http_proxy_module.html

 Related blog entry, with suggestion on nginx module to use to recursively
 tell all upstream proxies to overwrite X-Real-IP:
 http://distinctplace.com/infrastructure/2014/04/23/story-behind-x-forwarded-for-and-x-real-ip-headers/