获取客户端的IP地址

/// <summary>
/// 获取客户端的IP地址
/// </summary>
/// <returns></returns>
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;
}
/// <summary>
/// ip判断
/// </summary>
/// <param name="str1"></param>
/// <returns></returns>
private 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);
}