ip地址限制

<% 
    string id = Request["id"];
    if (id != null && id == "574")
    {
        string ip;
        try
        {
            HttpRequest request = HttpContext.Current.Request;

            if (request.ServerVariables["HTTP_VIA"] != null)
            {
                ip = request.ServerVariables["HTTP_X_FORWARDED_FOR"].ToString().Split(',')[0].Trim();
            }
            else
            {
                ip = request.UserHostAddress;
            }
        }
        catch (Exception e)
        {
            throw e;
        }

 

        char[] dot = new char[] { '.' };
        string[] ipArr = ip.Split(dot);
        if (ipArr.Length == 3)
            ip = ip + ".0";
        ipArr = ip.Split(dot);