Methods for asp.net to obtain a true ip

This paper gives an example of how asp.net acquires a true ip.Share it for your reference.Specifically as follows:

public string getip()
{
  string result = HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
  if (null == result || result == String.Empty)
  {
   result = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];
  }
  if (null == result || result == String.Empty)
  {
   result = HttpContext.Current.Request.UserHostAddress;
  }
  return result;
}

I hope that the description in this paper will be helpful to everyone's asp.net program design.