获取客户端IP

/// <summary>
/// 获取客户端IP
/// </summary>
        public static string GetClientIP()
        {
            string userIP;
            if (HttpContext.Current.Request.ServerVariables["HTTP_VIA"] == null)
            {
                userIP = HttpContext.Current.Request.UserHostAddress;
            }
            else
            {
                userIP = HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
            }
            return userIP;
        }