获取客户端真实IP

    ///  <summary> 
    ///  取得客户端真实IP。如果有代理则取第一个非内网地址 
    ///  </summary> 
    public static string GetIPAddress
    {
        get
        {
            var result = HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
            if (!string.IsNullOrEmpty(result))
            {
                //可能有代理 
                if (result.IndexOf(".") == -1)        //没有“.”肯定是非IPv4格式 
                    result = null;
                else
                {
                    if (result.IndexOf(",") != -1)
                    {
                        //有“,”，估计多个代理。取第一个不是内网的IP。 
                        result = result.Replace("  ", "").Replace("'", "");
                        string[] temparyip = result.Split(",;".ToCharArray());
                        for (int i = 0; i < temparyip.Length; i++)
                        {
                            if (IsIPAddress(temparyip[i])
                                    && temparyip[i].Substring(0, 3) != "10."
                                    && temparyip[i].Substring(0, 7) != "192.168"
                                    && temparyip[i].Substring(0, 7) != "172.16.")
                            {
                                return temparyip[i];        //找到不是内网的地址 
                            }
                        }
                    }
                    else if (IsIPAddress(result))  //代理即是IP格式 
                        return result;
                    else
                        result = null;        //代理中的内容  非IP，取IP 
                }

            }

            string IpAddress = (HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"] != null && HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"] != String.Empty) ? HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"] : HttpContext.Current.Request.ServerVariables["HTTP_X_REAL_IP"];

            if (string.IsNullOrEmpty(result))
                result = HttpContext.Current.Request.ServerVariables["HTTP_X_REAL_IP"];

            if (string.IsNullOrEmpty(result))
                result = HttpContext.Current.Request.UserHostAddress;

            return result;
        }
    }


    ///  <summary>
    ///  判断是否是IP地址格式  0.0.0.0
    ///  </summary>
    ///  <param  name="str1">待判断的IP地址</param>
    ///  <returns>true  or  false</returns>
    public static bool IsIPAddress(string str1)
    {
        if (string.IsNullOrEmpty(str1) || str1.Length < 7 || str1.Length > 15) return false;

        const string regFormat = @"^d{1,3}[.]d{1,3}[.]d{1,3}[.]d{1,3}$";

        var regex = new Regex(regFormat, RegexOptions.IgnoreCase);
        return regex.IsMatch(str1);
    }