Develop Reference

Detect when ethernet cable is plugged

I'm trying to detect when an Ethernet cable is plugged-in or unplugged but i have some probleme and i don't know if i'm doing this good or not.
I'm using NetworkChange.NetworkAddressChanged
to detect when the network change
and then NetworkInterface.GetAllNetworkInterfaces() for checking if Ethernet connexion is available or not with the property .OperationalStatus.
But when i search for the Ethernet connexion in all the network interfaces, it return me what i'm looking for, but it always return me the Bluetooth connection with it.
Here is the code :
public Form1()
{
InitializeComponent();
NetworkChange.NetworkAddressChanged += new NetworkAddressChangedEventHandler(AddressChangedCallback);
Console.ReadLine();
}
static void AddressChangedCallback(object sender, EventArgs e)
{
NetworkInterface[] adapters = NetworkInterface.GetAllNetworkInterfaces();
foreach (NetworkInterface myInterface in adapters)
{
//if (n.Description.ToLower().Contains("ethernet")){
//if (n.NetworkInterfaceType.ToString().ToLower().Contains("ethernet")){
IPInterfaceProperties properties = n.GetIPProperties();
if (myInterface.NetworkInterfaceType == NetworkInterfaceType.Ethernet)
{
Console.WriteLine(myInterface.Description + " ........... : " + myInterface.OperationalStatus);
Console.WriteLine("NetworkInterfaceType : " + myInterface.NetworkInterfaceType);
}
}
}
At the beginning, i was trying to check the name of the connection and looks if contains the "Ethernet" word, but it appears (if i'm not wrong) sometimes the connection name does not contain "Ethernet".
Do you have some tips for always bring the good connection (without the bluetooth)?
Am i wrong in my approach?
I'm testing it on a Surface Pro 3... but maybe i have the Bluetooth problem because of that?
Despite that, i need it to work even on device like this.

This can be done by checking its operational status as:
foreach (System.Net.NetworkInformation.NetworkInterface net in System.Net.NetworkInformation.NetworkInterface.GetAllNetworkInterfaces())
{
if (net.OperationalStatus ==
System.Net.NetworkInformation.OperationalStatus.Up)
Console.WriteLine("N/w connected");
else
Console.WriteLine("N/w not connected");
}

This links shows how to do it with Powershell, but one of the cases uses WMI.
http://www.powershellmagazine.com/2013/04/04/pstip-detecting-wi-fi-adapters/
And this links shows a interesting property that can help sometimes:
https://msdn.microsoft.com/en-us/library/aa394217(v=vs.85).aspx
GatewayCostMetric
Data type: uint16 array
Access type: Read-only Array
of integer cost metric values (ranging from 1 to 9999) to be used in
calculating the fastest, most reliable, or least resource-intensive
routes. This argument has a one-to-one correspondence with the
DefaultIPGateway property.

Unable to get the IP Address of network printer?

I need to find the IP address of the installed printers on my laptop. I move my laptop between different locations and networks. Each network has its own set of ip addresses. The laptop has different printers installed for each location with all connections being made wirelessly.
In using the below code (.net 4.0), the QueuePort.Name returns:
WSD-27e3f972-cdc7-459d-b0c1-20e8410fb1db.0032 and
192.168.1.12_1
Since these are network printers, I assume these have to resolve to a real IP Address??
Where am I going wrong? Or is there a better way? Any help is really appreciated.
IEnumerable<Printer> GetLocalPrinters()
{
EnumeratedPrintQueueTypes[] enumerationFlags = { EnumeratedPrintQueueTypes.Local, EnumeratedPrintQueueTypes.Connections };
LocalPrintServer printServer = new LocalPrintServer();
var x = printServer.GetPrintQueues(enumerationFlags).Select(y =>
new Printer
{
Fullname = y.FullName,
QueuePortName = y.QueuePort.Name,
Location = y.Location
})
.OrderBy( z => z.QueuePortName);
return x;
}

The portname is NOT the IP address. Sometimes they are the same text.
They answer appears to be here:
Determine the IP Address of a Printer in C#
Edited 31-Oct-2011:
Query the WMI for the printer port IP address.
using System;
using System.Management;
namespace WMI_example_01
{
class Program
{
static void Main(string[] args)
{
var scope = new ManagementScope(#"\\.\root\cimv2");
var query = new ObjectQuery("SELECT * FROM win32_tcpipprinterport");
var searcher = new ManagementObjectSearcher(scope, query);
var collection = searcher.Get();
foreach(var col in collection)
{
Console.WriteLine("Port name: {0}\tHostAddress: {1}", col["Name"], col"HostAddress"]);
}
}
}
}

The printing queue has a corresponding port that is handled by the port monitor.
There are different port monitors (not only standard monitors like TCPMON and WSD but also custom and vendor-specific), as far as I know, there is no universal way to deal with all kinds of them.
From the provided port name, I assume you are dealing with the WSD port. Here things become a bit tricky, I suggest you read my answer https://stackoverflow.com/a/63705944/4700228 for the solution.

How do you determine which adapter is used?

I have a need to figure out which adapter is used when a connection is created. In other words, if I have multiple NIC cards (i.e. wireless, lan, etc) on my machine, which card is being used for the connection?
If anyone can point me in the right direction...

In C#
foreach(var nic in NetworkInterface.GetAllNetworkInterfaces.Where(n => n.OperationalStatus == OperationStatus.UP)
{
if(nic.GetIsNetworkAvailable())
{
//nic is attached to some form of network
}
}
VB .NET
ForEach nic in NetworkInterface.GetAllNetworkInterfaces.Where(Function(n) n.OperationalStatus = OperationStatus.UP)
If nic.GetIsNetworkAvailable() Then
//nic is attached to some form of network
End If
Next
This will only test active working Network Interfaces that are connected to an active network.

Why don't you use the MAC address?

Maybe you could map it by the MAC Address:
var nics = NetworkInterface.GetAllNetworkInterfaces();
foreach (var nic in nics)
{
if (nic.OperationalStatus == OperationalStatus.Up)
{
var mac = nic.GetPhysicalAddress().ToString();
if (mac == "your:connections:mac:address")
{
/* ... */
}
}
}
The "your:connections:mac:address" part you can figure out following this method, using the IP address of the LocalEndPoint.
How do I obtain the physical (MAC) address of an IP address using C#?
It's not beautiful, but it could work.

Get MAC Address when network adapter is disabled?

Is there any way i can retrieve MAC Address when Network Adapter is disabled in .net?
Thanks in advance,

It is not possible to get the MAC address of an adapter which is disabled: this is because getting the MAC address requires querying the driver, and the driver for a disabled adapter is not loaded (source).
You can, however get the MAC address of an adapter which is not currently connected.
The WMI route is no good here, because it shows the MAC address as null for adapters which are not connected. The good news is that the NetworkInterface.GetAllNetworkInterfaces() route works just fine:
// using System.Net.NetworkInformation;
var nics = NetworkInterface.GetAllNetworkInterfaces();
// pick your NIC!
var selectedNic = nics.First();
var macAddress = selectedNic.GetPhysicalAddress().ToString();

Refer this link.
http://msdn.microsoft.com/en-us/library/system.net.networkinformation.physicaladdress.aspx
The example here displays physical address of all interface irrespective of their operational stage. HTH.

You can use WMI:
public static string GetMACAddress()
{
ManagementClass mc = new ManagementClass("Win32_NetworkAdapterConfiguration");
ManagementObjectCollection moc = mc.GetInstances();
string MACAddress=String.Empty;
foreach(ManagementObject mo in moc)
{
if(MACAddress==String.Empty) // only return MAC Address from first card
{
MACAddress= mo["MacAddress"].ToString() ;
}
mo.Dispose();
}
return MACAddress;
}

Using MS PowerShell command get-NetAdapter one can get the disabled network adapter's MAC Address.
More info at get-NetAdapter

Checking static or dynamic IP address in C# .NET?

I am building a pretty basic form app.
I can get a list of IP addresses available on the local machine. However, I want to also determine how these addresses are obtained (e.g. DHCP or static). How can I tell if a static IP address is configured on the system?
The goal is to inform a novice end-user (who may have no knowledge of the network setup, or how to obtain it) what static IP addresses are available. And, if no static address exist, inform them that one needs to be setup.
TIA

Better use Net.NetworkInformation due to better performance compared to WMI
using System.Net.NetworkInformation;
NetworkInterface[] niAdpaters = NetworkInterface.GetAllNetworkInterfaces();
private Boolean GetDhcp(Int32 iSelectedAdpater)
{
if (niAdpaters[iSelectedAdpater].GetIPProperties().GetIPv4Properties() != null)
{
return niAdpaters[iSelectedAdpater].GetIPProperties().GetIPv4Properties().IsDhcpEnabled;
}
else
{
return false;
}
}

You can use WMI to get network adapter configuration.
For an example, have a look at http://www.codeproject.com/KB/system/cstcpipwmi.aspx. The 'DhcpEnabled' property on the network adapter should tell you if the address is obtained via dhcp or not.

Unfortunately you'll probably have to use WMI. There might be another way, but this is the only way that I know.
This code will output all of the information about every adapter on your system. I think the name is "DHCPEnabled" of the property you want.
ManagementObjectSearcher searcherNetwork =
new ManagementObjectSearcher("root\\CIMV2",
"SELECT * FROM Win32_NetworkAdapterConfiguration");
foreach (ManagementObject queryObj in searcherNetwork.Get())
{
foreach (var prop in queryObj.Properties)
{
Console.WriteLine(string.Format("Name: {0} Value: {1}", prop.Name, prop.Value));
}
}

I use two method(s) as follows:
public static string GetLocalIPAddress()
{
var host = Dns.GetHostEntry(Dns.GetHostName());
foreach (var ip in host.AddressList)
{
if (ip.AddressFamily == AddressFamily.InterNetwork)
{
return ip.ToString();
}
}
return "unknown";
}
public static string GetLocalIpAllocationMode()
{
string MethodResult = "";
try
{
ManagementObjectSearcher searcherNetwork = new ManagementObjectSearcher("root\\CIMV2", "SELECT * FROM Win32_NetworkAdapterConfiguration");
Dictionary<string, string> Properties = new Dictionary<string, string>();
foreach (ManagementObject queryObj in searcherNetwork.Get())
{
foreach (var prop in queryObj.Properties)
{
if (prop.Name != null && prop.Value != null && !Properties.ContainsKey(prop.Name))
{
Properties.Add(prop.Name, prop.Value.ToString());
}
}
}
MethodResult = Properties["DHCPEnabled"].ToLower() == "true" ? "DHCP" : "Static";
}
catch (Exception ex)
{
ex.HandleException();
}
return MethodResult;
}
GetLocalIpAllocationMode() will tell you whether the ip is static or allocated via dhcp, whereas GetLocalIPAddress() will tell you the local ip itself.

The answers here helped me with my own project, but I had to do some research before I found out how to use the suggested method.
Adding using System.Management; to your code doesn't work by itself. You need to add a reference to System.Management before the namespace will be recognized. (For new people like me who tried this and were getting the error "managementclass could not be found").