获取本机外网的ip，C#

   /// <summary>
    /// 获取全部信息
    /// </summary>
    /// <returns>一段网页代码</returns>
    static Dictionary<string, object> getOutMessage()
    {
        WebClient client = new WebClient();
        client.Encoding = System.Text.Encoding.Default;
        string response = client.UploadString("http://pv.sohu.com/cityjson?ie=utf-8", "");
        Dictionary<string, object> obj =null;
        if(response!=null)
        {
            response = response.Substring(response.IndexOf("{"), (response.IndexOf("}")- response.IndexOf("{"))+1);
            obj=KeyValueCombination(response);
        }
        return obj;
    }


    static Dictionary<string, object> KeyValueCombination(string str)
    {
        JavaScriptSerializer serializer = new JavaScriptSerializer();
        Dictionary<string, object> json = (Dictionary<string, object>)serializer.DeserializeObject(str);
        return json;
    }


    static string getOutIp()
    {
        Dictionary<string, object> response = getOutMessage();
        if (response != null)
        {
            return response["cip"].ToString();
        }
        else
        {
            return null;
        }
    }