c# - Query Local IP Address

Question

I have the need to know my actual local IP address (i.e. not the loopback address) from a Windows 8 WinRT/Metro app. There are several reasons I need this. The simplest is that in the UI of the app I'd like to show some text like "Your local network IP address is: [IP queried from code]".

We also use the address for some additional network comms. Those comms are perfectly valid because it all works if I look at the IP address in the Control Panel, then hard-code it into the app. Asking the user in a dialog to go look at the address and manually enter it is something I really, really want to avoid.

I would think it wouldn't be a complex task to get the address programmatically, but my search engine and StackOverflow skills are coming up empty.

At this point I'm starting to consider doing a UDP broadcast/listen loop to hear my own request and extract the address from that, but that really seems like a hackey kludge. Is there an API somewhere in the new WinRT stuff that will get me there?

Note that I said "WinRT app. That means the typical mechanisms like Dns.GetHostEntry or NetworkInterface.GetAllInterfaces() aren't going to work.

Answer 1

After much digging, I found the information you need using NetworkInformation and HostName.

NetworkInformation.GetInternetConnectionProfile retrieves the connection profile associated with the internet connection currently used by the local machine.

NetworkInformation.GetHostNames retrieves a list of host names. It's not obvious but this includes IPv4 and IPv6 addresses as strings.

Using this information we can get the IP address of the network adapter connected to the internet like this:

public string CurrentIPAddress()
{
    var icp = NetworkInformation.GetInternetConnectionProfile();

    if (icp != null && icp.NetworkAdapter != null)
    {
        var hostname =
            NetworkInformation.GetHostNames()
                .SingleOrDefault(
                    hn =>
                    hn.IPInformation != null && hn.IPInformation.NetworkAdapter != null
                    && hn.IPInformation.NetworkAdapter.NetworkAdapterId
                    == icp.NetworkAdapter.NetworkAdapterId);

        if (hostname != null)
        {
            // the ip address
            return hostname.CanonicalName;
        }
    }

    return string.Empty;
}

Note that HostName has properties CanonicalName, DisplayName and RawName, but they all seem to return the same string.

We can also get addresses for multiple adapters with code similar to this:

private IEnumerable<string> GetCurrentIpAddresses()
{
    var profiles = NetworkInformation.GetConnectionProfiles().ToList();

    // the Internet connection profile doesn't seem to be in the above list
    profiles.Add(NetworkInformation.GetInternetConnectionProfile());

    IEnumerable<HostName> hostnames =
        NetworkInformation.GetHostNames().Where(h => 
            h.IPInformation != null &&
            h.IPInformation.NetworkAdapter != null).ToList();

    return (from h in hostnames
            from p in profiles
            where h.IPInformation.NetworkAdapter.NetworkAdapterId ==
                  p.NetworkAdapter.NetworkAdapterId
            select string.Format("{0}, {1}", p.ProfileName, h.CanonicalName)).ToList();
}