Wake-on-LAN (WoL)

Configure the Wake-on-LAN (WoL) Clients

This configuration is applied to any device that needs to be remotely powered on automatically after recovering from a power failure. i.e., the Wake-on-LAN clients

Install wakeonlan and ethtool on your device.

sudo apt install wakeonlan
sudo apt install ethtool

Identify the ethernet interface of your device.

ip a

It will be the one that has the 192.168.xx.xx IP address assigned. For example:

Check your existing Wake-on-LAN status. Replace enp2s0with the actual ethernet interface of your device.

sudo ethtool enp2s0 | grep "Wake-on"

If you see the following, you can proceed to the next sub-section. Else, continue following along.

	Supports Wake-on: pumbg
	Wake-on: g

If you see Wake-on: d or any other letter here, it means wake-on-lan is disabled or not optimally configured so you need to change this letter to g.

sudo ethtool -s enp2s0 wol g

Next, make this configuration persistent even after rebooting your system.

sudo nano /etc/netplan/01-network-manager-all.yaml

Add the following lines to your file.

  ethernets:
    <ETHERNET_INTERFACE>:
      wakeonlan: true

Example of how your file should look like.

network:
  version: 2
  renderer: NetworkManager
  ethernets:
    enp2s0:
      dhcp4: true
      wakeonlan: true

CTRL+O, ENTER, CTRL+X to save and exit.

Apply the new configuration.

sudo netplan apply

Enable Wake-on-LAN in BIOS

Wake-on-LAN may not be enabled on your devices by default. If so, you will need to plug in a monitor and keyboard into your device to enable it.

  1. Restart your device and press F2 repeatedly during boot to enter BIOS Setup.

  2. Select Advanced, then select the Power menu.

  3. Expand the Secondary Power Settings sub-menu and set Wake-on-LAN from S4/S5 to: Power On - Normal Boot.

  4. Press F10 to save and exit the BIOS Setup.

Set up Wake-on-LAN server

You will need to use a Raspberry Pi or a similar low-powered device without a standby power mode for this setup. i.e., no on/off button, turns on once connected to a power source.

This device will serve as the Wake-on-LAN server that sends "power on" signals to all your other devices in the same network after recovering from a power failure.

OPTIONAL: Connect your Raspberry Pi to your WiFi network

Install the network manager package.

sudo apt install network-manager -y

Connect to your WiFi network.

sudo nmtui

Follow the terminal UI to Activate a connection>>Choose WiFi SSID>>Enter password. Just like how you would normally connect to a WiFi network!

Once you are connected to your WiFi network, press ESC to exit the nmtui terminal UI.

Configure the Wake-on-LAN server

Create a wake-on-LAN script on your Raspberry Pi that covers all your other devices.

sudo nano /usr/local/bin/wake_devices

Paste the following content:

Add more devices as needed as new lines in the format ["Name"]="MAC Address" within the declare -A devices=(...) segment.

#!/bin/bash
# Wake all devices by sending magic packets using wakeonlan
# Logs are saved to a designated folder, including device names

# Define the folder to store logs
LOG_FOLDER="$HOME/wol_logs"
LOG_FILE="$LOG_FOLDER/wol_$(date '+%Y-%m-%d_%H-%M-%S').log"

# Create the log folder if it doesn't exist
mkdir -p "$LOG_FOLDER"

# Define a list of devices with their names and MAC addresses
declare -A devices=(
    ["testnode"]="aa:bb:cc:dd:ee:ff" # replace with your actual device name and MAC address 
    # Add more devices as needed as new lines here in the format ["Name"]="MAC"
)

# Start logging
echo "WOL Script started at $(date)" > "$LOG_FILE"
echo "Log file: $LOG_FILE" >> "$LOG_FILE"

# Send a WOL packet to each device
for name in "${!devices[@]}"; do
    mac="${devices[$name]}"
    echo "Sending WOL packet to $name ($mac)..." | tee -a "$LOG_FILE"
    wakeonlan "$mac" >> "$LOG_FILE" 2>&1
    if [ $? -eq 0 ]; then
        echo "Successfully sent WOL packet to $name ($mac)" | tee -a "$LOG_FILE"
    else
        echo "Failed to send WOL packet to $name ($mac)" | tee -a "$LOG_FILE"
    fi
done

# End logging
echo "WOL Script finished at $(date)" >> "$LOG_FILE"
echo "Logs saved to $LOG_FILE"

CTRL+O, ENTER, CTRL+X to save and exit.

Make this script executable.

sudo chmod +x /usr/local/bin/wake_devices

We want this script to run automatically whenever our WOL server restarts after a power failure. Create a new systemd service file to run the script at startup.

sudo nano /etc/systemd/system/wake_devices.service

Add the following content:

[Unit]
Description=Wake-on-LAN script to wake all devices
After=network.target

[Service]
ExecStartPre=/bin/sleep 300
ExecStart=/usr/local/bin/wake_devices
Restart=on-failure
RestartSec=5s
User=raspberrypi 
#use your actual system user above

[Install]
WantedBy=multi-user.target

We want the WOL script to run only after all your other devices have completely turned off in the event of a instant recovery following a power failure, which will cause this script to fail its purpose. Hence the deliberate 300 second delay imposed in this service file via /bin/sleep 300

Load and run the WOL service.

sudo systemctl daemon-reload
sudo systemctl enable wake_devices.service
sudo systemctl start wake_devices.service
sudo systemctl status wake_devices.service
sudo journalctl -u wake_devices

Use CTRL+C to exit the monitoring/logging view.

Manual Wake-on-LAN via Telegram Bot (Optional)

This is useful as a backup to the automated WOL setup above in case you need to manually "wake up" your devices remote after recovery from a power failure.

Key Features:

  1. Does not require opening ports to each of your devices

  2. Conveniently "wakes up" all your devices via Telegram. i.e., without needing to download new apps

  3. Run on your Wake-on-LAN server. e.g., Raspberry Pi that runs 24/7

  4. Requires the "Setup an automated Wake-on-LAN server" sub-section above to be completed

Create a new Telegram bot by following the steps below.

  1. Open Telegram and Message the BotFather:

    • Search for "BotFather" in Telegram and start a conversation.

  2. Create a New Bot:

    • Send /newbot to the BotFather.

    • Follow the instructions in the BotFather chat to name your bot and get its API token.

  3. Save the API Token:

    • Example token: 123456789:ABCDEFGHIJKLMNOPQRSTUVWXYZ.

  4. Add the Bot to Your Private Group:

    • Invite the bot to your Telegram group.

  5. Get Your Chat ID:

    • Use the bot to retrieve the chat ID:

      • Send a message in the Telegram group with your bot

      • Navigate to https://api.telegram.org/bot<YourBOTToken>/getUpdates on your browser while replacing <YourBOTToken> with your actual Telegram bot API token

Install dependencies on your WoL server (Raspberry Pi).

sudo apt install python3-pip
sudo apt install python3-dotenv
sudo apt install python3-python-telegram-bot

Create a new folder to store the bot files.

sudo mkdir -p /usr/local/bin/TG_WOL_BOT

Create the .env file to store private and sensitive information such as your Telegram bot token and chat ID.

sudo nano /usr/local/bin/TG_WOL_BOT/.env

Add your Bot API Token and Chat ID as variables into .env

#example
BOT_TOKEN=123456789:ABCDEFGHIJKLMNOPQRSTUVWXYZ
ALLOWED_CHAT_ID=-123456789

CTRL+O, ENTER, CTRL+X to save and exit.

Secure the .env file so that only your current user can access the file.

sudo chmod 600 /usr/local/bin/TG_WOL_BOT/.env
sudo chown -R $USER:$USER /usr/local/bin/TG_WOL_BOT

Create the Telegram bot script.

sudo nano /usr/local/bin/TG_WOL_BOT/WOL_bot.py

Paste the following content:

from telegram.ext import Application, CommandHandler
import subprocess
import os
from dotenv import load_dotenv

# Load environment variables
load_dotenv("/usr/local/bin/TG_WOL_BOT/.env")

BOT_TOKEN = os.getenv("BOT_TOKEN")
ALLOWED_CHAT_ID = int(os.getenv("ALLOWED_CHAT_ID"))

async def start(update, context):
    """Send a welcome message."""
    chat_id = update.effective_chat.id
    if chat_id != ALLOWED_CHAT_ID:
        await update.message.reply_text("Unauthorized!")
        return
    await update.message.reply_text("Hi! I'm your Wake-on-LAN bot.")

async def wol_command(update, context):
    """Run the Wake-on-LAN script."""
    chat_id = update.effective_chat.id
    # Check if chat_id is authorised
    if chat_id != ALLOWED_CHAT_ID:
        await update.message.reply_text("Unauthorized!")
        return
    try:
        await update.message.reply_text("Running Wake-on-LAN script...")
        # Run the WoL script
        result = subprocess.run(
            ["/usr/local/bin/wake_devices"],
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE,
            text=True
        )
        # Log results & notify user
        if result.returncode == 0:
            await update.message.reply_text("Wake-on-LAN script executed successfully!")
        else:
            await update.message.reply_text(f"Script failed with error:\n{result.stderr}")
    except Exception as e:
        await update.message.reply_text(f"An error occurred: {str(e)}")

def main():
    """Start the bot."""
    if not BOT_TOKEN:
        print("Error: BOT_TOKEN environment variable not set.")
        return
    if not ALLOWED_CHAT_ID:
        print("Error: ALLOWED_CHAT_ID environment variable not set.")
        return

    # Create the application instance
    application = Application.builder().token(BOT_TOKEN).build()

    # Add command handlers
    application.add_handler(CommandHandler("start", start))
    application.add_handler(CommandHandler("wol", wol_command))

    # Start the bot
    application.run_polling()

if __name__ == "__main__":
    main()

CTRL+O, ENTER, CTRL+X to save and exit.

How to use the Telegram Bot: Type /start and then /wol in the chat group created with your bot.

  • /start: Greets the user and checks if they are authorized.

  • /wol: Executes the wake_devices script

The Authorization Check ensures only messages from the allowed Chat ID trigger actions.

Make this python file executable.

sudo chmod +x /usr/local/bin/TG_WOL_BOT/WOL_bot.py
sudo chown -R $USER:$USER /usr/local/bin/TG_WOL_BOT

Create a systemd service file for the bot:

sudo nano /etc/systemd/system/WOL_bot.service

Add the following content:

[Unit]
Description=Telegram Bot for Wake-on-LAN
After=network.target

[Service]
ExecStart=/usr/bin/python3 /usr/local/bin/TG_WOL_BOT/WOL_bot.py
Restart=always
RestartSec=5s
User=raspberrypi
#use your actual system user above
WorkingDirectory=/usr/local/bin/TG_WOL_BOT

[Install]
WantedBy=multi-user.target

CTRL+O, ENTER, CTRL+X to save and exit.

Load and run the WOL bot service.

sudo systemctl daemon-reload
sudo systemctl enable WOL_bot.service
sudo systemctl start WOL_bot.service
sudo systemctl status WOL_bot.service
sudo journalctl -fu WOL_bot.service

Use CTRL+C to exit the monitoring/logging view.

Use a DNS that allows connection to Telegram

This tells the network manager of your Raspberry Pi (systemd-resolved) to ALWAYS use these DNS servers.

sudo mkdir -p /etc/systemd/resolved.conf.d
echo -e "[Resolve]\nDNS=8.8.8.8 8.8.4.4" | sudo tee /etc/systemd/resolved.conf.d/custom-dns.conf
sudo systemctl restart systemd-resolved

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