Tag Archives: Wake-on-Lan
Wake-on-Lan (WoL) in C#
Wake on LAN is a computer networking standard that allows devices to be powered on when they receive a specific network message, if your device supports this feature.
In this example we will demonstrate how to craft this “magic” packet in C#. The concept of the packet is fairly simple. The packet must contain anywhere in the payload six (6) 255 bytes in a row (FF in hexadecimal) followed by the MAC address of the device repeated sixteen times.
As an example, if your device MAC address is 01-00-00-00-00-02 the payload will look like this:
1 | FFFFFFFFFFFF010000000002010000000002010000000002010000000002010000000002010000000002010000000002010000000002010000000002010000000002010000000002010000000002010000000002010000000002010000000002010000000002 |
You can find the implementation of WoL in C# below:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 | var macAddress = "01-00-00-00-00-02"; // Our device MAC address macAddress = Regex.Replace(macAddress, "[-|:]", ""); // Remove any semicolons or minus characters present in our MAC address var sock = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp) { EnableBroadcast = true }; int payloadIndex = 0; /* The magic packet is a broadcast frame containing anywhere within its payload 6 bytes of all 255 (FF FF FF FF FF FF in hexadecimal), followed by sixteen repetitions of the target computer's 48-bit MAC address, for a total of 102 bytes. */ byte[] payload = new byte[1024]; // Our packet that we will be broadcasting // Add 6 bytes with value 255 (FF) in our payload for (int i = 0; i < 6; i++) { payload[payloadIndex] = 255; payloadIndex++; } // Repeat the device MAC address sixteen times for (int j = 0; j < 16; j++) { for (int k = 0; k < macAddress.Length; k += 2) { var s = macAddress.Substring(k, 2); payload[payloadIndex] = byte.Parse(s, NumberStyles.HexNumber); payloadIndex++; } } sock.SendTo(payload, new IPEndPoint(IPAddress.Parse("255.255.255.255"), 0)); // Broadcast our packet sock.Close(10000); |
And the result…
Feel free to leave your questions or feedback in the comment section below.
