asp.net获取用户登陆IP

/// <summary>          ///  获取用户登陆IP         ///   </summary>          ///   <returns> 返回用户IP </returns>          public   string  GetIp()          {            string user_IP;            if(System.Web.HttpContext.Current.Request.ServerVariables["HTTP_VIA"]!=null)            {                 user_IP=System.Web.HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"].ToString();             }            else            {                 user_IP=System.Web.HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"].ToString();             }             return user_IP;        }          /// <summary>        /// 获取用户登陆IP        /// </summary>        /// <returns>返回用户IP</returns>          public   string  GetIp2()         {            return System.Web.HttpContext.Current.Request.ServerVariables.GetValues("REMOTE_ADDR")[0];        }         /// <summary>        /// 获取用户登陆IP        /// </summary>       /// <returns>返回用户IP</returns>          public   string  GetIp3()         {           return System.Web.HttpContext.Current.Request.UserHostAddress;        }