ASP.NET 获取客户端IP （无视代理）

public static string ClientIP()
{
string result = String.Empty;

result = HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
if (result != null && result != String.Empty)
{
//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["REMOTE_ADDR"];

if (null == result || result == String.Empty)
result = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];

if (result == null || result == String.Empty)
result = HttpContext.Current.Request.UserHostAddress;

return result;
}

#region bool IsIPAddress(str1) 判断是否是IP格式
/**/
/// <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 (str1 == null || str1 == string.Empty || str1.Length < 7 || str1.Length > 15) return false;

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

Regex regex = new Regex(regformat, RegexOptions.IgnoreCase);
return regex.IsMatch(str1);
}
#endregion