asp.net获取访问者ip地址的函数

/// <summary>
/// 获取IP地址
/// </summary>
     public static string IPAddress
     {
         get
         {
             string userIP;
             // HttpRequest Request = HttpContext.Current.Request;
             HttpRequest Request = HttpContext.Current.Request; // ForumContext.Current.Context.Request;
             // 如果使用代理，获取真实IP
             if (Request.ServerVariables["HTTP_X_FORWARDED_FOR"] != "")
                 userIP = Request.ServerVariables["REMOTE_ADDR"];
             else
                 userIP = Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
             if (userIP == null || userIP == "")
                 userIP = Request.UserHostAddress;
             return userIP;
         }
     }