waker

HTTP interface to send WakeOnLan magic packet remotely

High level view

The goal of this micro service is to remotely wake a computer from a phone or a laptop.

The target is a device that is supposedly expensive to keep running, the waker server is a smaller device that can be always on and the client is a device that I have at hand (e.g. phone or laptop).

The waker server receives an HTTP request and broadcast the magic packet on the local subnet before sending a confirmation message back to the client.

Installation

go install github.com/maxime915/waker@latest

Usage

Usage of waker:
  -address string
    	server binding address (with port) (default ":0")
  -broadcast string
    	UDP address to send the datagram to (with port) (default "192.168.0.255:9")
  -killable
    	allow the route /kill to work (default true)
  -target string
    	6 bytes MAC address of the target
  -verbose
    	gives more network information at start-up

A few notes:

• To use the default value for the address, set -verbose to see which port is being listened to.
• broadcast may be something other than a broadcast address, if that use fits your need
• target is mandatory to build the magic packet, no default value can be useful
• while it is possible to set the address using waker -address :0 ... it is mandatory to use the equal sign for the boolean flags (e.g. waker -killable=false ...).

Access with GET http://addr:port/wake, the success message is "200 - Magic packet sent", if any error that couldn't be detected at startup occurs, "500 - Error while sending magic packet" is returned.

To remotely kill the server, send GET http://addr:port/kill, if the server is killable the response is "200 - shutting down" otherwise it is "400 - server cannot be killed remotely".

Example

$ waker -target 00:00:00:00:00:00 -address ":900" -verbose &
[1] 39757
waker is running, killable: true
	TCP socket [::]:900
	MAC target 00:00:00:00:00:00
	UDP target 192.168.0.255:9
$ curl ":900/wake"
200 - Magic packet sent
$ curl ":900/kill"
200 - shutting down
[1]  + 39757 done       waker -target 00:00:00:00:00:00 -address ":900" -verbose

waker sends the UDP datagram to launch the WakeOnLan procedure on the interface 00:00:00:00:00:00. The datagram is sent on the broadcast address of the local subnet (192.168.0.255:9) by default.

Building

There are two target: "waker" and "piwaker". The first one is the default for the locall architecture and the second one is targeted towards Raspberry Pi. make all builds both version.

made with go1.16

Example of simple plug&play configuration

If your waker server needs only one instance of waker running at once, here is a simple configuration for plug-and-play usage. This supposes the logged-in user is not sudoers and has auto-login. Git and Go must be installed beforehand.

• go install github.com/maxime915/waker@latest
• edit .profile or equivalent to add

if ! pidof waker; then
    waker -target 00:00:00:00:00:00 -address 192.168.0.27:9009 2> errs.log &
fi

• waker will now start at every login (if no instance is running).

Log-able errors

While waker is built with safety concerns in mind, some errors might still come up at run-time and be logged to stderr, here are the main causes :

• inability to write an UDP datagram to the broadcast address
• inability to write an HTTP response
• any error from http.Serve