Initial import.

Dockerfile

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+FROM alpine:3.16.0
+
+ENV PORT=18888
+
+COPY . /app
+RUN apk add --no-cache netcat-openbsd awake
+
+EXPOSE $PORT
+
+CMD ["/app/run.sh"]

README.md

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+# wake-on-lan-service
+
+Remotely wake up your servers ... as-a-service!
+
+**The problem:** Docker prevents bridge-networked containers from sending
+wake-on-lan packets outside of the Docker network. That means standard Docker
+containers can't wake up remote machines. As a work-around, you can put them
+on the Docker host network, but that has security and interoperability
+implications—you may not want to expose your containers that way.
+
+**The solution:** wake-on-lan-service runs on Docker's host network and sends
+wake-on-lan packets *on behalf of* other containers running on a standard
+bridge network. This allows them to wake up remote machines—without themselves
+having to be on the host network.
+
+You might find this service useful for use cases like running [Home
+Assistant](https://www.home-assistant.io/) in a Docker container without
+putting it on the host network—while still allowing it to wake up remote
+machines.
+
+Source at https://projects.torsion.org/witten/wake-on-lan-service
+
+
+## How it works
+
+This service listens on a port for TCP requests containing a MAC address to
+send a wake-on-lan packet to. It expects plain TCP requests, not HTTP.
+
+
+## Environment variables
+
+ * `PORT`: The TCP port to listen on for wake-on-lan requests, defaults to 18888.
+
+
+## Example
+
+### Running the service
+
+```
+$ sudo docker run --detach --name wake-on-lan-service --host network \
+    --env PORT=18888
+    witten/wake-on-lan-service
+```
+
+### Using the service
+
+From within another container running on a Docker bridge network (so, no need
+to run on the host network), execute:
+
+```
+echo "00:00:0A:BB:28:FC" | nc -N host.docker.internal 18888
+```
+
+This example uses the OpenBSD netcat variant to send a TCP packet containing
+the requested MAC address to wake. The packet is sent to port 18888 on the
+host.
+
+For this to work, you may need to configure your client container to support
+the special `host.docker.internal` host. E.g., `docker run --add-host
+host.docker.internal:host-gateway ...`
+
+Alternatively, on Linux, you can try using the IP `172.17.0.1`.
+
+
+## Security
+
+Note that no authorization is performed on the service request, so be aware
+that anyone with network access to this service can wake arbitrary hosts by
+MAC address.

run.sh

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+#!/bin/sh
+
+set -u
+
+while true; do
+    mac=$(nc -l -p "$PORT" | sed 's/[^a-f0-9:]//g')
+    awake "$mac"
+done