C# Get the MAC Address of the Host's Physical Network Interface Card

Supports Windows and Linux

            var macAddr =
                (
                from nic in NetworkInterface.GetAllNetworkInterfaces()
                where nic.OperationalStatus == OperationalStatus.Up
                select nic.GetPhysicalAddress().ToString()
                ).FirstOrDefault();

            Console.WriteLine(macAddr);

There may be multiple network interfaces in the host, such as Ethernet, WLAN, VPN, etc. The method above will obtain the MAC address of the most suitable network interface.