The six projects at a glance
| Project | Core software | What the old laptop needs |
|---|---|---|
| Offline library | Kiwix (ZIM archives) | Storage space and a local network |
| Experimental router/firewall | OPNsense | x86-64 CPU, enough RAM, two network interfaces |
| Aircraft tracker | RTL-SDR receiver, 1,090 MHz antenna, ADS-B software on Linux | A USB port and a Linux install |
| Mini data center | Proxmox VE, K3s | Plenty of RAM and CPU virtualization support |
| Hacking practice | OWASP Juice Shop in Docker | Docker capability |
| Wi-Fi detective | Kismet on Linux | A Wi-Fi adapter that supports monitor mode |
1. An offline library for your local network
Kiwix packs content such as Wikipedia, technical documentation and books into compressed ZIM files. White's idea is to load a laptop with that content and let other devices browse it over the local network.
Kiwix's own documentation backs the sharing part. The Electron version of its app includes a built-in server. To reach it from another device, you tick "Allow external network access", which lasts for that session only. The app then shows a local IP address to open in a browser.
Three caveats from that documentation:
- External access is off by default. Only turn it on if you trust every device on your network, because the traffic is plain HTTP, not HTTPS.
- The server only accepts connections from private IP ranges, not the public internet.
- An archive is a snapshot. To refresh it, you download a new one.
Wikipedia archives also come in different sizes. Kiwix offers "mini", "nopic" and "maxi" editions, which matters if the old laptop has a small drive.
2. A sandbox router with OPNsense
OPNsense is an open-source firewall and routing platform. According to its hardware documentation, it targets x86-64 hardware, so a very old 32-bit laptop is out. The documented tiers are:
- Minimum: a 1 GHz dual-core CPU and 3 GB of RAM. This covers standard features that don't need disk writes.
- Reasonable: a 1 GHz dual-core CPU, 4 GB of RAM and a 40 GB SSD.
- Recommended: a 1.5 GHz multi-core CPU, 8 GB of RAM and a 120 GB SSD.
Features that write to disk, such as a caching proxy or intrusion detection and prevention, push the requirements up.
The article suggests a USB-to-Ethernet adapter to get separate WAN and LAN ports. That is sensible, but not every adapter will work. OPNsense is built on FreeBSD and shares its hardware compatibility, so check the adapter's chipset against the FreeBSD hardware list before buying. OPNsense's documentation also says Intel network chipsets tend to deliver higher throughput at lower CPU load.
Treat this as a place to practice VLANs, firewall rules and VPNs. Don't treat it as a guaranteed replacement for your household router.
3. An aircraft-tracking station
The recipe is a cheap RTL-SDR USB receiver, a 1,090 MHz antenna and software such as ADS-B Ultrafeeder on Linux. Aircraft with ADS-B broadcast their position, altitude, speed and identity. Your receiver picks up whatever is in range.
One limit applies here. This is local reception, not worldwide tracking. The article gives no range figures, receiver model or antenna placement advice, so I won't promise any. Reception depends on your antenna, your location and what's overhead. Kismet's documentation lists ADS-B support through RTL-SDR, but that is a separate route from the Ultrafeeder one the article names.
4. A "miniature data center" with Proxmox and K3s
The plan is to run Proxmox VE, create several virtual machines, and build a small K3s Kubernetes cluster with one control-plane node and a couple of workers. Then you deploy containers and deliberately knock nodes offline.
Proxmox's published figures show how loose the "minimum" is:
- Testing only: a 64-bit CPU with Intel VT or AMD-V (which KVM full virtualization needs), at least 1 GB of RAM, a disk and one NIC.
- Recommended: at least 2 GB for the Proxmox OS and services, plus memory for the guests. ZFS and Ceph need extra.
K3s's own documentation lists minimums of 2 cores and 2 GB of RAM for a server node, and 1 core and 512 MB for an agent. These exclude whatever your workloads use. Add them up and the article's advice of 8 GB at minimum, 16 GB preferably, looks reasonable. That figure is the author's practical estimate, not a documented requirement.
A cluster of VMs on one laptop is still one machine. Shutting down a "node" is a fine lesson in Kubernetes scheduling. Shutting down the laptop takes everything with it, so this is a learning tool, not redundancy.
K3s also recommends SSDs, because its database performance depends on disk speed. If your old laptop still has a spinning drive, fix that first.
5. A hacking playground you're allowed to attack
OWASP Juice Shop is a deliberately insecure web app. OWASP's Developer Guide says it covers the entire OWASP Top Ten plus other real-world flaws. It runs on Windows, macOS and Linux through Docker. The guide's quick start is:
- Make sure the Docker daemon is running.
- Pull the image with
docker pull bkimminich/juice-shop. - Start it with
docker run --rm -p 3000:3000 bkimminich/juice-shop. - Open
[url]http://localhost:3000/#/[/url]in a browser.
OWASP says it includes built-in coding challenges and an optional tutorial mode that guides newcomers. It is also used for training, capture-the-flag events and testing security scanners. Juice Shop is the only thing here you have permission to attack. Pointing the same techniques at a neighbor's router or a real website is still illegal.
6. A Wi-Fi detective with Kismet
The idea is to install Linux and Kismet to see nearby access points, channel activity and packets. This is the project where an old laptop is most likely to disappoint, and it comes down to the Wi-Fi adapter.
Kismet's documentation explains that capturing raw Wi-Fi packets needs "monitor mode". It says most drivers in the Linux kernel support this, but not all do. It also says Windows has nearly no public monitor-mode drivers, so this is a Linux job. Its Linux datasource page adds that some driver variants silently fail to enable monitor mode. If the built-in card won't cooperate, a USB adapter known to support monitor mode is the usual workaround.
There is also a fallback. Scanning mode works with nearly any Wi-Fi card but sees only access points, not client devices. It also cannot see packet data. It is still useful for spotting crowded channels.
Kismet is passive for the most part, but packet capture can pick up data from nearby devices. Use it on networks you own or are authorized to assess.
Which project should you start with?
- Weakest hardware: Kiwix is the gentlest. It needs storage more than horsepower.
- A spare network port: OPNsense is worth trying if you can add a second interface.
- 8 GB of RAM or more: Proxmox with K3s becomes realistic.
- Linux and Docker already set up: Juice Shop is the cheapest security lab here.
- Compatible Wi-Fi hardware: Kismet and ADS-B are the most hardware-dependent, so check the adapter or radio before you invest time.
The article's premise is sound: a laptop you don't mind breaking is a better lab than a production machine. The caveats are about hardware compatibility, honest RAM budgeting and staying inside your own network. None of them rule the projects out.