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 

//获取本机的公网IP
privatestaticstring GetIP()
{
string tempip ="";
try
{
WebRequest wr = WebRequest.Create("http://city.ip138.com/ip2city.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("[") +1;
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();