I’ve been working on a cross-platform VMM library. Part of that involves a userspace NAT implementation that lets guest VMs access the network without requiring root privileges or TUN/TAP devices. Running the network stack in userspace also lets us enforce network policies on the guest, restricting which hosts and ports it can access.

We have integration tests that boot minimal Linux VMs and run commands via the console. One of those tests pings the gateway to verify networking works. It was using ping -c 1 with a FIXME: “Using -c 1 because -c 3 or higher causes the test to hang.” I decided to figure out why.

Back in 2021, I found an unrestricted file upload vulnerability on my Siglent SDS1104X-E oscilloscope that could be escalated to remote code execution. This is a writeup of that bug.

One of the main things I missed on my Elegoo Mars Pro 3D Printer was remote access over WiFi. I wanted to upload files, print and keep track of print status while I’m away from the printer. Luckily, the Elegoo Mars Pro exposes a serial port on some of its motherboard pins, allowing for it to be controlled with a Raspberry Pi Zero W. I wrote a software called mariner for controlling it over HTTP and here I document my current setup.