Check out Your Network Connectivity

Check out Your Network Connectivity

Problem

You need to determine the characteristics of the network adapters currently on the machine.

Solution

Use the DisplayNICInfo method shown in Figure to display all of the characteristics of the currently existing network adapters using the System.Net.NetworkInformation. NetworkInterface class. Calling the GetAllNetworkInterfaces method will get the list of current adapters as NetworkInterface instances. Information such as the adapter ID, MAC address, status, and NIC type is available on the NetworkInterface class.

Setting the SMTP server properties

Allowing an IP address to access the SMTP server

Allowing access to local machine (IP address 127.0.0.1)

Local machine granted access to SMTP server

To see all of the IP information for an adapter, call the GetIPProperties method on the NetworkAdapter instance and pass the IPInterfaceProperties collection to the DisplayInterfaceProperties method (implemented shortly).

DisplayNICInfo method

private static void DisplayNICInfo()
{
     //Display current network adapter states
    NetworkInterface[] adapters = NetworkInterface.GetAllNetworkInterfaces();
    Console.WriteLine("Network Adapter Information:");
    foreach (NetworkInterface n in adapters)
    {
        Console.WriteLine("\tId: {0}", n.Id);
        Console.WriteLine("\tPhysical (MAC) Address: {0}",
            n.GetPhysicalAddress().ToString());
        Console.WriteLine("\tDescription: {0}", n.Description);
        Console.WriteLine("\tName: {0}", n.Name);
        Console.WriteLine("\tOperationalStatus: {0}",
                n.OperationalStatus.ToString());
        Console.WriteLine("\tInterface type: {0}",
                n.NetworkInterfaceType.ToString());
        Console.WriteLine("\tSpeed: {0}", n.Speed);
        IPInterfaceProperties ipProps = n.GetIPProperties();
        DisplayInterfaceProperties(ipProps);
    }
    Console.WriteLine("");
}

The DisplayInterfaceProperties method shown in Figure breaks down and displays all of the IP configuration information, such as DHCP and WINS addresses, gateway and DNS addresses, assigned IP addresses for the adapter, as well as multicast and unicast information.

DisplayInterfaceProperties method

private static void DisplayInterfaceProperties(IPInterfaceProperties props)
{
    Console.WriteLine("\t\tDns Suffix : {0}", props.DnsSuffix);
    Console.WriteLine("\t\tAnycast Addresses:");
    foreach (IPAddressInformation ipInfo in props.AnycastAddresses)
    {
        Console.WriteLine("\t\t\t{0}", ipInfo.Address.ToString());
        Console.WriteLine("\t\t\tIsDnsEligible: {0}", ipInfo.IsDnsEligible);
        Console.WriteLine("\t\t\tIsTransient: {0}", ipInfo.IsTransient);
    }

    Console.WriteLine("\t\tDHCP Server Addresses:");
    foreach (IPAddress ipAddr in props.DhcpServerAddresses)
    {
        Console.WriteLine("\t\t\t{0}", ipAddr.ToString());
    }

    Console.WriteLine("\t\tDNS Addresses:");
    foreach (IPAddress ipAddr in props.DnsAddresses)
    {
        Console.WriteLine("\t\t\t{0}", ipAddr.ToString());
    }

    Console.WriteLine("\t\tGateway Addresses:");
    foreach (GatewayIPAddressInformation gatewayIPInfo in props.GatewayAddresses)
    {
        Console.WriteLine("\t\t\t{0}", gatewayIPInfo.Address.ToString());
    }

    Console.WriteLine("\t\tUnicast Addresses:");
    foreach (UnicastIPAddressInformation uniIPInfo in props.UnicastAddresses)
    {
        Console.WriteLine("\t\t\tAddress: {0}",
                uniIPInfo.Address.ToString());
        Console.WriteLine("\t\t\tPreferred Lifetime: {0}",
                uniIPInfo.AddressPreferredLifetime);
        Console.WriteLine("\t\t\tValid Lifetime: {0}",
                uniIPInfo.AddressValidLifetime);
        Console.WriteLine("\t\t\tDHCP Lease Lifetime: {0}",
                uniIPInfo.DhcpLeaseLifetime);
        Console.WriteLine("\t\t\tPrefix Origin: {0}",
                uniIPInfo.PrefixOrigin.ToString());
        Console.WriteLine("\t\t\tSuffix Origin: {0}",
                uniIPInfo.SuffixOrigin.ToString());
    }

    Console.WriteLine("\t\tMulticast Addresses:");
    foreach (MulticastIPAddressInformation multiIPInfo in props.MulticastAddresses)
    {
        Console.WriteLine("\t\t\tAddress: {0}", multiIPInfo.Address.ToString());
        Console.WriteLine("\t\t\tPreferred Lifetime: {0}",
                     multiIPInfo.AddressPreferredLifetime);
        Console.WriteLine("\t\t\tValid Lifetime: {0}",
                    multiIPInfo.AddressValidLifetime);
        Console.WriteLine("\t\t\tDHCP Lease Lifetime: {0}",
                    multiIPInfo.DhcpLeaseLifetime);
        Console.WriteLine("\t\t\tPrefix Origin: {0}",
                    multiIPInfo.PrefixOrigin.ToString());
        Console.WriteLine("\t\t\tSuffix Origin: {0}",
                    multiIPInfo.SuffixOrigin.ToString());
    }

    Console.WriteLine("\t\tWINS Server Addresses:");
    foreach (IPAddress ipAddr in props.WinsServersAddresses)
    {
        Console.WriteLine("\t\t\t{0}", ipAddr.ToString());
    }
    Console.WriteLine("");

}

The .NET runtime also provides event notifications when the network address changes for an adapter or the network availability state changes, through the NetworkChange. NetworkAddressChanged and NetworkChange.NetworkAvailabilityChanged events. In the TestNetInfo method, you hook up for these events, then handle them in the NetworkChange_NetworkAddressChanged and NetworkChange_NetworkAvailabilityChanged methods. When the availability event fires, the NetworkAvailabilityEventArgs object can be accessed to see if the network is available through the IsAvailable property. The network address event does not supply information about what address changed, so you simply call DisplayNICInfo again.

	public static void TestNetInfo()
	{
	    // Hook up for network events
	    NetworkChange.NetworkAddressChanged += new
	NetworkAddressChangedEventHandler(NetworkChange_NetworkAddressChanged);

	    NetworkChange.NetworkAvailabilityChanged += new
	NetworkAvailabilityChangedEventHandler(NetworkChange_NetworkAvailabilityChanged);

	    DisplayNICInfo();
	}

	static void NetworkChange_NetworkAddressChanged(object sender, EventArgs e)
	{
	    // A network address changed; redisplay the info
	    Console.WriteLine("*** NEW NETWORK INFORMATION IS AVAILABLE *** ");
	    DisplayNICInfo();
	}

	static void NetworkChange_NetworkAvailabilityChanged(object sender,
	    NetworkAvailabilityEventArgs e)
	{
	    if(e.IsAvailable)
	        Console.WriteLine("Network is now available");
	    else
	        Console.WriteLine("Network is no longer available");
	}

The output is shown here:

	Network Adapter Information:
	    Id: {XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}
	    Physical (MAC) Address: XXXXXXXXXXXX
	    Description: Broadcom NetXtreme 57xx Gigabit Controller - Packet Scheduler
	Miniport
	    Name: Local Area Connection
	    OperationalStatus: Up
	    Interface type: Ethernet
	    Speed: 100000000
	        Dns Suffix :
	        Anycast Addresses:
	        DHCP Server Addresses:
	            255.0.0.1
	        DNS Addresses:
	            255.0.0.1
	        Gateway Addresses:
	            255.0.0.1
	        Unicast Addresses:
	            Address: 255.0.0.101
	            Preferred Lifetime: 52434
	            Valid Lifetime: 52434
	            DHCP Lease Lifetime: 52434
	            Prefix Origin: Dhcp
	            Suffix Origin: OriginDhcp
	        Multicast Addresses:
	            Address: 224.0.0.1
	            Preferred Lifetime: 0
	            Valid Lifetime: 0 
	            DHCP Lease Lifetime: 24
	            Prefix Origin: 48
	            Suffix Origin: WellKnown
	            Address: 255.255.255.250
	            Preferred Lifetime: 0 
	            Valid Lifetime: 0 
	            DHCP Lease Lifetime: 24
	            Prefix Origin: Other 
	            Suffix Origin: WellKnown
	        WINS Server Addresses:
	            0.0.0.0
	            0.0.0.0

	    Id: MS TCP Loopback interface
	    Physical (MAC) Address:
	    Description: MS TCP Loopback interface 
	    Name: MS TCP Loopback interface
	    OperationalStatus: Up 
	    Interface type: Loopback
	    Speed: 10000000
	        Dns Suffix :
	        Anycast Addresses:
	        DHCP Server Addresses:
	        DNS Addresses:
	        Gateway Addresses:
	        Unicast Addresses:
	            Address: 127.0.0.1
	            Preferred Lifetime: 3170812643
	            Valid Lifetime: 3170812643
	            DHCP Lease Lifetime: 3170812643
	            Prefix Origin: Manual
	            Suffix Origin: Manual
	        Multicast Addresses:
	            Address: 224.0.0.1
	            Preferred Lifetime: 0
	            Valid Lifetime: 0 
	            DHCP Lease Lifetime: 7733284
	            Prefix Origin: 110
	            Suffix Origin: WellKnown
	        WINS Server Addresses:

Discussion

Knowing the configuration of the network you are running on can come in handy when attempting to troubleshoot connectivity issues. Being able to get an event notification when connectivity is lost or an adapter changes its IP address is a great benefit, as it allows you to write code that can recover gracefully and instruct the user what has happened. However you want to use it, there is a lot of valuable information provided in the NetworkInformation namespace that can make life a bit better for developers working in a connected environment.

See Also

See the "System.Net.NetworkInformation Namespace," "Network Interface Class," and "IPInterfaceProperties Class" topics in the MSDN documentation.