// 접속 대기
Socket client = tcplistener.AcceptSocket();

// 2초 동안 수신하지 못하면 타임아웃으로 설정
client.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, 2000 );

TcpClient client = new TcpClient("127.0.0.1", 12345);
client.ReceiveTimeout = 2000;
client.SendTimeout = 2000;

IPAddress[] address = Dns.GetHostAddresses(Dns.GetHostName());

var adapters = System.Net.NetworkInformation.NetworkInterface.GetAllNetworkInterfaces();
            
foreach (var adapter in adapters)
{
	if (adapter.OperationalStatus.Equals(System.Net.NetworkInformation.OperationalStatus.Up))
	{
		var properties = adapter.GetIPProperties();
		foreach (var ipInfo in properties.UnicastAddresses)
		{
			var ip = ipInfo.Address;
			if (!System.Net.IPAddress.IsLoopback(ip))
			{
				Console.WriteLine("IP = " + ip);
				Console.WriteLine("MAC = " + adapter.GetPhysicalAddress());
			}
		 }
	 }
}

using System;
using System.Net;
using System.Runtime.InteropServices;

[DllImport("iphlpapi.dll", ExactSpelling=true)]
private static extern int SendARP( int DestIP, int SrcIP, byte[] pMacAddr, ref int PhyAddrLen );

private byte[] getMacAddress(string val)
{
    return getMacAddress(IPAddress.Parse(val));
}

private byte[] getMacAddress(IPAddress addr)
{
    byte[] mac = new byte[6];
    int len = mac.Length;
    int r = SendARP( BitConverter.ToInt32(addr.GetAddressBytes(), 0), 0, mac, ref len );

    return mac;
}

IPEndPoint remoteIP = new IPEndPoint(IPAddress.Broadcast, 10002);

byte[] data = new byte[16];
Socket s = new Socket( AddressFamily.InterNetwork, SocketType.Dgram, 
                               ProtocolType.Udp );

s.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.IpTimeToLive, 16);

// 브로드캐스트는 옵션으로 사용 가능하도록 한다 
s.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.Broadcast, 1);

s.SendTo(data, data.Length, SocketFlags.None, remoteIP);

// 보낼 곳
IPEndPoint remoteIP = new IPEndPoint(IPAddress.Parse("192.168.11.2"), 80);

// 보낼 데이터
byte[] data = new byte[16];

// UDP 소켓 만들기
Socket s = new Socket( AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.U에 );

// TTL를 설정
// TTL라는 것은…→　http://e-words.jp/w/TTL-2.html
s.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.IpTimeToLive, 255);

// 데이터를 보낸다
s.SendTo(data, 0, data.Length, SocketFlags.None, remoteIP);

using System.Management; // 참조 설정에 System.Management 를 추가

ManagementClass mc = new ManagementClass("Win32_PerfRawData_Tcpip_NetworkInterface");
ManagementObjectCollection moc = mc.GetInstances();

foreach (ManagementObject mo in moc)
{
    // 정보를 표시
    Console.WriteLine("이름     = {0}", mo["Name"]);
    Console.WriteLine("접속 속도 = {0} Mbps", 
                  Convert.ToInt32(mo["CurrentBandwidth"]) / 1000 / 1000);

    Console.WriteLine("------");
}