How to determine remote IP address in ActionWebService API's

Hello all!

I trying to create XMLRPC service with ActionWebService plugin and
Rails 2.0.2. I use conventional layered based API.

This is my controller:
class RpcController < ApplicationController
  skip_before_filter :verify_authenticity_token
  web_service_dispatching_mode :layered
  web_service :user,

And service:
class UserRpcService < ActionWebService::Base
  web_service_api UserRpcAPI
  def auth(login, passwd)
    user = User::find(:first, :conditions => {:login => login, :passwd
=> passwd})
    raise UserAuthException, "Auth failed" unless user.instance_of?

In method UserRpcService.auth i need to know from which remote IP this
RPC call is come (for logging or restrictions etc.).