I’ll be speaking at linux.conf.au 2018 in Sydney. Jittertrap testing infrastructure is slowly improving. The idea is to include known test data so that the front-end rendering can be verified and refactored. I expect a sprint over the holidays and some new bugs for lca. :) Clean up of the tn40xx dri…

New hardware for BufferUpr has arrived! I’m working on adding Wifi capability into the product and with new hardware comes new challenges. Challenge: Find a simple way to list all the network interfaces in the system, including the PCIe slot and MAC address for each. Solution: find /sys/devices/pci0…

Fedora 23 (the current release at the time of writing) ships an outdated version of SciPy that doesn’t include the spectrogram function. Installing the latest Scipy was kind-of a pain, so I thought I’d record some instructions for future-me and share it with you. These instructions install dependenc…

This is the story of my first expensive lesson in Digital Signal Processing. It is about JitterTrap, the free software that powers BufferUpr. The premise of BufferUpr is to combine commodity hardware with open source software to create a product that can measure data stream delays of 1-100 milliseco…

It was the year of 2015 and people were still developing new applications in PHP… but for those who could no longer accept the idea of installing a system-wide LAMP stack, there was a new-old fassionable thing: Containers! This is a quick howto for creating a throw-away container for messing around …

Sometimes there is good reason to talk to yourself. You might be doing a sound check, for example. Likewise, it can be useful to route IP packets between two interfaces on the same machine using an external path. One reason to do this is to test other network devices like routers or switches. For ma…

I received some encouraging comments on G+ from Jesper Dangaard Brouer about my previous post on DSCP, Linux and VLAN priorities. Those comments and the work linked to (here) points to a few long-standing (but minor) issues with the way DSCP priorities are handled in Linux. Some DSCP values, like E…

I recently discovered a flaw in the VLAN implementation I did at work. It seemed that the normal TCP traffic had the correct VLAN priorities applied, but audio streaming UDP traffic did not. This was due to DSCP being applied to the streaming audio and the fact that the VLAN device’s egress-qos-map …

This concerns the proliferation of netlink libraries and a lack of direction and documentation. Background: I’ve configured a router with netem (see Bandwidth Throttling with NetEM Network Emulation and the tc-netem man page) to test Tieline devices under various delay and loss network conditions. I…

After finally completing task 01 of the Eudyptula Challenge, I’d like to share a few things I’ve learned, without divulging any crucial details about the task or solution. tl;dr Pay attention. Patience… Maybe it’s just the timezone, but the turn-around time for a response to a submission meant that …