近来搞电脑的远程启动搞上瘾了。使用网络启动（Wake on Lan），确实带来很多玩法。为了进一步降低电费，减少电脑非使用时段（例如晚上睡觉时段）待机而产生的功耗，采用ESP32C3（刷上MicroPython）来作为远程开机设备。即：

• 普通x86电脑，在晚上或无需使用的时间正常关机，并开启网络启动功能。
• ESP32C3开发板保持24小时开机并联网，可在需要时远程启动所需x86电脑。

于是找了下，在MicroPython上发送Wake on Lan的实现代码。参考了以下文章：

• https://pypi.org/project/wakeonlan/
• https://www.cnblogs.com/Yogile/p/16488281.html

整理出可用代码，保存为文件wol.py，如下：

"""
Small module for use with the wake on lan protocol.

Reference:
- https://pypi.org/project/wakeonlan/
- https://www.cnblogs.com/Yogile/p/16488281.html
"""
import socket
import ubinascii


BROADCAST_IP = "255.255.255.255"
DEFAULT_PORT = 9
SO_BROADCAST = 20

def create_magic_packet(macaddress: str) -> bytes:
    """
    Create a magic packet.

    A magic packet is a packet that can be used with the for wake on lan
    protocol to wake up a computer. The packet is constructed from the
    mac address given as a parameter.

    Args:
        macaddress: the mac address that should be parsed into a magic packet.

    """
    if len(macaddress) == 17:
        sep = macaddress[2]
        macaddress = macaddress.replace(sep, "")
    elif len(macaddress) == 14:
        sep = macaddress[4]
        macaddress = macaddress.replace(sep, "")
    if len(macaddress) != 12:
        raise ValueError("Incorrect MAC address format")
    #return bytes.fromhex("F" * 12 + macaddress * 16)
    return ubinascii.unhexlify("F" * 12 + macaddress * 16)


def send_magic_packet(
    *macs: str,
    ip_address: str = BROADCAST_IP,
    port: int = DEFAULT_PORT,
    interface: str = None
) -> None:
    """
    Wake up computers having any of the given mac addresses.

    Wake on lan must be enabled on the host device.

    Args:
        macs: One or more macaddresses of machines to wake.

    Keyword Args:
        ip_address: the ip address of the host to send the magic packet to.
        port: the port of the host to send the magic packet to.
        interface: the ip address of the network adapter to route the magic packet through.

    """
    try:
        sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, 1)
        
        if interface is not None:
            sock.bind((interface, 0))
        sock.setsockopt(socket.SOL_SOCKET, SO_BROADCAST, 1)
        sock.connect((ip_address, port))
        for mac in macs:
            packet = create_magic_packet(mac)
            sock.send(packet)
            print("send magic packet to MAC [%s]" % (mac))
    except:
        print('send magic packet failed')
        pass
    finally:
        sock.close()

使用示例：

import wol

mac = '12:ab:12:ab:12:ab' # 必填参数。要启动电脑的网卡MAC
broadcastIp = '192.168.0.255'  # 可选参数。广播的地址，一般填对应网段的255地址

wol.send_magic_packet(mac, ip_address=broadcastIp)