Dns.GetHostEntry returns wrong IP addresses on Windows Mobile

Question

This is on a handheld connected to my computer via USB, using the Compact Framework:

When I call Dns.GetHostEntry("") or Dns.GetHostEntry(IPAddress.Loopback) to get the IPAddresses of the handheld, I get the IPAddresses of my host computer. But when I send a packet from the handheld to my computer, they come from a different address.

Is there a way to stop it from doing this? Would calling the DLLs directly via P/Invoke fix it?

The handheld isn't connected via WiFi or Bluetooth. The only connection is over USB.

Answer 1

When you call Dns.GetHostEntry("") I'd think you'd get back a single entry in the IPHostEntry.AddressList of 127.0.0.1 (and, in fact, that's what a quick test shows). Dns.GetHostEntry(IPAddress.Loopback) returns two entries: 127.0.0.1 and ::1.

Neither is returning the IP address of the host PC, and neither should return the IP address of the device. If you want the IP address of the device, use something like this:

IPHostEntry hostent = Dns.GetHostEntry(Dns.GetHostName());

foreach (var addr in hostent.AddressList)
{
    Debug.WriteLine(addr.ToString());
}