rails request.remote_ip

    # Determines originating IP address.  REMOTE_ADDR is the standard
    # but will fail if the user is behind a proxy.  HTTP_CLIENT_IP and/or
    # HTTP_X_FORWARDED_FOR are set by proxies so check for these if
    # REMOTE_ADDR is a proxy.  HTTP_X_FORWARDED_FOR may be a comma-
    # delimited list in the case of multiple chained proxies; the last
    # address which is not trusted is the originating IP.
    def remote_ip
      remote_addr_list = @env['REMOTE_ADDR'] && @env['REMOTE_ADDR'].scan(/[^,\s]+/)

      unless remote_addr_list.blank?
        not_trusted_addrs = remote_addr_list.reject {|addr| addr =~ TRUSTED_PROXIES}
        return not_trusted_addrs.first unless not_trusted_addrs.empty?
      end
      remote_ips = @env['HTTP_X_FORWARDED_FOR'] && @env['HTTP_X_FORWARDED_FOR'].split(',')

      if @env.include? 'HTTP_CLIENT_IP'
        if ActionController::Base.ip_spoofing_check && remote_ips && !remote_ips.include?(@env['HTTP_CLIENT_IP'])
          # We don't know which came from the proxy, and which from the user
          raise ActionControllerError.new(<<EOM)
IP spoofing attack?!
HTTP_CLIENT_IP=#{@env['HTTP_CLIENT_IP'].inspect}
HTTP_X_FORWARDED_FOR=#{@env['HTTP_X_FORWARDED_FOR'].inspect}
EOM
        end

        return @env['HTTP_CLIENT_IP']
      end

      if remote_ips
        while remote_ips.size > 1 && TRUSTED_PROXIES =~ remote_ips.last.strip
          remote_ips.pop
        end

        return remote_ips.last.strip
      end

      @env['REMOTE_ADDR']
    end