martineden / whodis

Monitor local network for devices and announce them creepily

whodis

Monitor local network for devices and announce them creepily.

What is this?

This is a silly little service, designed to run on Ubuntu. You give it a list of MAC addresses and human readable names (like John Smith). When it detects a device joining your WiFi network it announces "John Smith has arrived" using text to speech.

The idea is that you can leave this running and (if you live on a hill like I do) when your friends are approaching your house their devices will automatically pick up your WiFi and whodis will tell you that they are approaching, so you can get the kettle on.

If a device has been disconnected for 10 minutes it will announce them again next time they reconnect (you can override this default in the settings file; see below).

Install it

Clone the repository and then run ./install.sh. You should run it using your ordinary user account. (i.e. do not run as root.)

It uses a JSON file at /etc/whodis/hosts to match up MAC addresses with names. The format is:

[
    {
        "address": "00:00:00:00:00:00",
        "name": "John Smith",
        "announce": true
    },
    {
        "address": "11:11:11:11:11:11",
        "name": "My printer",
        "announce": false
    }
]

For devices that you are not interested in announcing (such as your printer), you can create an entry and set announce to false.

Devices that do not have an entry in the hosts file will be announced as "Unknown device" to remind you to add them to the hosts file. You can see the associated MAC addresses by viewing the service log using journalctl --user-unit whodis -e.

You will need to restart the service (systemctl restart whodis) for changes to this file to take effect.

Settings

Create a JSON file at /etc/whodis/settings to override the default settings.

Setting key	Default value	Meaning
timeoutInSeconds	600s (10 minutes)	If a device has not been seen on the network for this long it will be forgotten, and re-announced next time it connects
checkFrequencyInSeconds	20s	How often the service should poll for ARP data to discover hosts

Here is a sample settings file showing the default values. All settings are optional (as is the settings file itself).

{
    "timeoutInSeconds": 600,
    "checkFrequencyInSeconds": 20
}

Run it from source

Clone the repo and then run ./gradlew :run. You will need a JDK already installed.

Troubleshooting

• Make sure sound is enabled (see below)
• Make sure that the host is connected to the WiFi if you want to announce WiFi devices
• Check journalctl -user-unit whodis -e

Enabling sound on Ubuntu server

Instructions from here:

sudo apt install alsa alsa-tools
sudo adduser $USER audio

Then reboot and run alsamixer to interactively set the volume.

Creating a new release

1. Update the version number in build.gradle
2. Run ./release.sh.
3. Create a new release in GitHub and upload the zip file from build/distributions.

whodis's Issues

Install script fails due to privilege mixing

Now that the service is installed as a user service some commands must be run not as root. But the install.sh script is setup assuming it is run as sudo.

I need to separate out the parts that need root privilege and make sure they get run using the correct user.