c#获取外网IP代码片段

public static string getIp()
{
string strHostName = Dns.GetHostName();
IPAddress[] strAddress = Dns.GetHostAddresses(Dns.GetHostName());
//IPAddress strAddress = Dns.Resolve(strHostName).AddressList[0];
string IpValue = strAddress.ToString();
string strUrl = "http://www.ip138.com/ip2city.asp"; //获得IP的网址了
Uri uri = new Uri(strUrl);
System.Net.WebRequest wr = System.Net.WebRequest.Create(uri);
System.IO.Stream s = wr.GetResponse().GetResponseStream();
System.IO.StreamReader sr = new System.IO.StreamReader(s, Encoding.Default);
string all = sr.ReadToEnd(); //读取网站的数据
int i = all.IndexOf("[") + 1;
string tempip = all.Substring(i, 15);
string ip = tempip.Replace("]", "").Replace(" ", "");//找出i
Console.WriteLine(ip);
return ip;
}