1。获取局域网ip      

IPAddress ipAddr = Dns.Resolve(Dns.GetHostName()).AddressList[0];//获得当前IP地址

string ip=ipAddr.ToString() ;

2。获取公网ip      

{    string tempip = "";    try    {        WebRequest wr = WebRequest.Create("http://www.ip138.com/ips138.asp");        Stream s = wr.GetResponse().GetResponseStream();        StreamReader sr = new StreamReader(s, Encoding.Default);        string all = sr.ReadToEnd(); //读取网站的数据        int start = all.IndexOf("您的IP地址是：[") + 9;        int end = all.IndexOf("]", start);        tempip = all.Substring(start, end - start);        sr.Close();        s.Close();    }    catch    {    }    return tempip;}

3.如果是ADSL上网，获取公网ip　　

string tempIP =string.Empty; if (System.Net.Dns.GetHostEntry(System.Net.Dns.GetHostName()).AddressList.Length >1)      tempIP = System.Net.Dns.GetHostEntry(System.Net.Dns.GetHostName()).AddressList[1].ToString();