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Question

How to get default NIC Connection Name in command line or C#

Answer 1

A:

You can get a list of them, but not the default (perhaps you can assume it is the first entry).

static void Main(string[] args)
{
  foreach (var nc in NetworkInterface.GetAllNetworkInterfaces())
  {
    Console.WriteLine(nc.Name);
  }

  Console.ReadLine();
}

leppie 2010-08-11 09:57:25

No, I don't need the list...

Mauro 2010-08-11 10:08:57

@Mauro: Then take the first or which ever one you want...

leppie 2010-08-11 10:09:51

Please don't take it personal, as the default should be taken programmatically, the list won't do the trick. If you say it is not possible and prove it, than I can take yours as an answer.Peace

Mauro 2010-08-11 10:13:12

@Mauro: IT all depends what defines the default. What makes 'Local Area Connection' the default? I have never seen such a setting in Windows. The closest thing I can think of is the routing metric on a per network basis.

leppie 2010-08-11 11:41:58

Answer 2

+1 A:

using System.Linq;
using System.Net.NetworkInformation;

var nic = NetworkInterface
     .GetAllNetworkInterfaces()
     .Where(i => i.NetworkInterfaceType != NetworkInterfaceType.Loopback && i.NetworkInterfaceType != NetworkInterfaceType.Tunnel)
     .FirstOrDefault();
var name = nic.Name;

or more beautiful condition:

.Where(i => !(
    new[] { NetworkInterfaceType.Loopback, NetworkInterfaceType.Tunnel }
    .Contains(i.NetworkInterfaceType)))

or if you want to practice in LINQ:

static IEnumerable<NetworkInterface> GetAllNetworkInterfaces(IEnumerable<NetworkInterfaceType> excludeTypes)
{
    var all = NetworkInterface.GetAllNetworkInterfaces();
    var exclude = all.Where(i => excludeTypes.Contains(i.NetworkInterfaceType));
    return all.Except(exclude);
}

Usage:

var nic = GetAllNetworkInterfaces(new[] { NetworkInterfaceType.Tunnel, NetworkInterfaceType.Loopback });

abatishchev 2010-08-11 10:06:18

Am I wrong or FirstOrDefault will give, if I have more than one, the first of the list and NOT the default?

Mauro 2010-08-11 10:08:17

@Mauro: `FirstOrDefault<T>` returns first from a list. If list is empty then `default(T)` (`null` for reference types)

abatishchev 2010-08-11 10:14:34

Yes I know :DThe "Default" concept I use here means "the connection that is in use, i.e. is the default".

Mauro 2010-08-11 10:17:20

@Mauro - What if several are in use?

fletcher 2010-08-11 10:19:48

@Mauro: :) Yea, sorry, Just first but not system default. Because there is no system default nic. It can be a nic for default route, which depends on a target given and in general - on routing table

abatishchev 2010-08-11 10:19:58

@Fletcher: you're right I should have only said "the default one"... as it seems by the registry starred connection name. What do you think?

Mauro 2010-08-11 10:25:19

Answer 3

+1 A:

You can use the WMI class Win32_NetworkAdapter to enumerate all the adapters and it has an Index property which might mean that the one with 0 or 1 as the Index is the default one, or one of the other properties might help to find the default one.

Something like this maybe:

Edit: Fixed broken code (this is at least more likely to work). But following what abatishchev said I think you might need to use Win32_NetworkAdapterConfiguration.IPConnectionMetric to find the default adapter...

ManagementClass mc = new ManagementClass("Win32_NetworkAdapter");
foreach (ManagementObject mo in mc.GetInstances())
{
     int index = Convert.ToInt32(mo["Index"]);
     string name = mo["NetConnectionID"] as string;
     if (!string.IsNullOrEmpty(name))
          textBox1.Text += name + Environment.NewLine;
}

ho1 2010-08-11 10:13:11

`var nic = new ManagementClass("Win32_NetworkAdapter").GetInstances().OfType<ManagementObject>().Select(mo => mo["NetConnectionID"] as string).Where(mo => !String.IsNullOrEmpty(mo)).FirstOrDefault();`

abatishchev 2010-08-11 11:01:13

Answer 4

+2 A:

As others have mentioned, there is no "Default" NIC adapter in Windows. The NIC used is chosen based on the destination network (address) and the metric.

For example, if you have two NICs and two different networks:

  10.1.10.1 - Local Area Connection (metric 20)
  10.1.50.1 - Local Area Connection 2 (metric 10)

And you want to connect to 10.1.10.15, Windows will choose Local Area Connection and route that way. Conversely, if you want to connect to 10.1.50.30, Windows will choose Local Area Connection 2.

Now, if you try to connect to 74.125.67.106 (google.com), Windows will choose Local Area Connection 2 because it has a lower metric value.

EDIT: Here is a great article explaining routing - http://www.windowsnetworking.com/articles_tutorials/Making-Sense-Windows-Routing-Tables.html
EDIT2: Spelling.

Hope this helps.

Jesse 2010-08-11 16:36:57

Thanks, I'll read the article.

Mauro 2010-08-12 14:40:18

Answer 5

+1 A:

This is a dirty way of doing it as it can be optimized by incorporating LINQ, etc

using System.Net.NetworkInformation;

List<NetworkInterface> Interfaces = new List<NetworkInterface>();
foreach (var nic in NetworkInterface.GetAllNetworkInterfaces())
{
    if (nic.OperationalStatus == OperationalStatus.Up)
    {
        Interfaces.Add(nic);
    }
}


NetworkInterface result = null;
foreach (NetworkInterface nic in Interfaces)
{
    if (result == null)
    {
        result = nic;
    }
    else
    {
        if (nic.GetIPProperties().GetIPv4Properties() != null)
        {
            if (nic.GetIPProperties().GetIPv4Properties().Index < result.GetIPProperties().GetIPv4Properties().Index)
                result = nic;
        }
    }
}

Console.WriteLine(result.Name);

you'll probably want to tailor your results by using the results from nic.GetIPProperties() and nic.GetIPProperties().GetIPv4Properties()

entens 2010-09-08 17:01:57

Hi entens, thanks a lot. Last question is: is it possible to get the IPv4 SubnetMask (as is Windows Network Connection Details "window") form the NetworkInterface class?

Mauro 2010-09-09 07:32:21

You can access the `UnicastAddresses` array. Relevant info should be at the first index. So to get the subnet mask you would access `result.GetIPProperties().UnicastAddresses[0].IPv4Mask` according to the code in the answer. You might need to iterate over it to get what your looking for though.

entens 2010-09-09 14:49:08

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How to get default NIC Connection Name in command line or C#

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