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Pi-Alert - Network Device Discovery and Change Notifications

One of the things i really like about Eero was a notification about a new device joining my network.  I think it was really more based on a new lease being pulled from DHCP, but still it let me know when Family members or friends came by and got close enough to the network for their phones to join it.  Kind of an early warning notification.  

The real benefit to a system like this, is notification of a device on your network you aren't expecting or aware of. After moving to OPNSense as my Router / Firewall, and DD-WRT for my Wired / Wireless Access Points, I realized I kind of missed that feature of Eero.  Started looking around the web, and came across Pi-Alert.  A really simple network monitoring tool that can run on a Raspberry PI (or in my case on a LXC container running Debian 11 Bullseye), that simply looks at your arp tables and watches for changes between scans.  When it finds a change it sends an email to you as a notification.

It also has a really clean, simple interface that you can use for checking in as well.  As a bonus, it comes with the option to install Pi-hole to help you keep your network as ad-free as possible.

Installing Pi-Alert

What You'll Need

  • A Raspberry PI running Raspberry Pi OS, or a server running Debian (any other Linux distro may also work, but I haven't verified any others).
  • Curl, Wget, and Git installed on your chosen server
  • SMTP (Email Server Sending Credentials and Host Information)
  • About 10 Minutes of your time

Initial Setup

First, you'll need to make sure your chosen server is setup and ready to go. I personally setup a Debian 11 server in an LXC Container, but you can run this on any Linux machine most likely.   As stated in the name, you can also run it ona Raspberry Pi.  I suggest a Pi 4 if possible, but you can probabaly run it on a Pi 3 as well.

SSH Access

Wherever you run it, you'll want SSH access, so make sure to get that setup for your system.  There are too many ways and options for me to go into it, but do a quick web search and you'll find hundreds (if not thousands) of results on getting SSH access to your chosen server.

Curl Install

It's important that you have Curl installed on your server, as this is how you get the Pi-Alert install script to run it.  I also like to install the wget and git tools as well, so let's just install them altogether.

sudo apt install curl wget git -y

Installing Pi-Alert

Now we can run the Pi-alert install script with the command:

curl -sSL | bash

If you are saying, "Hold on!  I'm not comfortable just blindly running some script."  I hear you on that.  You can check out the script by going to this web address if you prefer.

Once the script starts to run, you can move through the installation wizard with relative easy.

In most cases I answered 'Yes' to any questions that were Yes/No, and I did opt to setup Pi-Hole on the server as well, but you are not required to do that.  Additionally, I did setup SMTP for email alerts, but again, you are not required to set this up.

Post Install

After your install completes, you'll get some information from Pihole as well as PiAlert.  You'll want to make note of the URLs used to access those sites on your network, as well as the initial password for your Pi-hole install if you choose to install it.

If you didn't get the Pi-hole password, you can change the Web Admin password for Pi-hole with the command:

pihole -a -p

Then enter your desired new password and confirm it when prompted.

Check out the video linked at the top for a detailed walk through of the install, as well as an overview of the PIAlert web interface.

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