Daniel Lublin – Software developer & factotum

I have extensive hands-on experience of software development and all sorts of information systems. As a generalist I move freely between technologies. With a pragmatic and problem-solving orientation. Comfortable in diverse and dynamic environments, enjoying interdisciplinary work.

Social and communicative, with much experience of working together with new people. Our systems are often built in cooperation, and designed to be collectively cared for. Striving for correctness and clarity, promoting reliable and maintainable software.

My competences include systems design and development in multiple programming languages, on diverse platforms and at various levels of the stack. Never afraid to try new things, to experiment and tinker. Iterate until success. Always learning and sharing the knowledge.

Working as a contractor/consultant from office in Malmö, and remote.

Selected assignments ¶

Tillitis, 2022–2023

• Research and development of TKey, a versatile USB security key. The Tkey runs custom applications loaded onto it and uses a Measured Boot style approach to security. Open source/hardware.
• Focus on end-to-end functionality and usability, from host programs and OS integrations, down to embedded system and hardware I/O interfaces. Development of host programs in Go, firmware and device apps in C, involving RISC-V assembly, and Verilog FPGA designs.
• Development of an SSH agent where the secret (private) key never leaves the TKey hardware – its first real use-case.
• Prototyping a U2F implementation (FIDO2 predecessor) for doing two-factor authentication (2FA) using TKey, usable for example on the Web.
• Continuous improvement of QEMU emulation machine, continuous integrations, and developer experience.

Mullvad, 2022

• Working in the team responsible for software running on the VPN provider’s numerous Wireguard servers.
• Development and maintenance of CI and testing of server software, public key provisioning system, and APIs.
• Research and prototyping of next-generation provisioning system.

Briar, 2021–

• Development of Briar, an Android app for secure, peer-to-peer communications. Decentralized operation without any intermediary servers; using Tor Onion Services, local WLAN and Bluetooth. Free and open-source software.

Remotive Labs, 2020–

• Automotive project involving small computers, various peripheral devices, network buses. Message brokering, network proxying, all sorts of integrations. Problem solving, feature implementation, security, user experience. Elixir, Go, C, APIs, GRPC, Protocol Buffers, Vue, Javascript, firmware build systems, Yocto/OpenEmbeded.

Kastelo, 2019–2020

• Developing a reverse HTTP tunnel-broker in Go, for use with a system for managing deployments of the file synchronization program Syncthing.
• Prototyping decentralized apps on Android. Building on top of Syncthing, using AOSP, Kotlin, Java, Go, GRPC, Protocol Buffers.

Axis Communications, Lund, 2016–2017

• Maintenance of a large build system based on OpenEmbedded, targeting misc devices and hardware platforms.
• Developing an extendable linting tool in Python for OpenEmbedded package recipes, running as part of Jenkins CI and giving developers continuous feedback on their changes submitted in Gerrit.
• Holding workshops on OpenEmbedded, bitbake, devtool etc. Working to solve developers’ frustrations with this fairly new in-house environment.
• Prototyping and evaluating the use of QEMU for running test-suites in the CI chain.

Beijer Electronics, Malmö, 2016

• Doing bring-up of U-Boot & Linux on custom ARM-based board. Schematics reading, RAM configuration, pin-muxing, device tree and driver associations. Including reading up parameters from ROM and other customizations. Distribution building using OpenEmbedded.

Netnod Internet Exchange, 2015

• Extending an invoicing system to support new DNS services, with formula-based invoice generation using customer data aggregated over time. Python, Django, Postgresql, Mysql.
• Built a test client for simulating customers, speaking to a REST API being developed for new services. Small tools for generating test zone-files. Minor extensions, endpoints, to the Django system.

During 2003–2011 I undertook, among other things, several longer journeys. Large parts of these by hitchhiking, but that’s way too many stories for a cv.

I was previously a C++ hacker and general factotum for an online RPG in Göteborg. Before that I was hacking at Roxen in Linköping, makers of early web servers.

Talkative section ¶

I do development around, not limited to: text-, network- and web-oriented systems, standardized and own protocols and APIs, databases, automation, data processing, system integrations. Both lower and higher levels of the stack. Adaptation, integration and new solutions – often based on free and open-source software.

Much knowledge of networking, Internet services and infrastructure. Familiar with various protocols and server implementations, both professionally, and from running services privately, hacking on code, reading RFCs. Buzz: TCP/IP, IPv6, iproute2, iptables, ARP, DNS & name servers, HTTP(S), SMTP, DHCP, IRC, XMPP, NTP/NTS. SSH, VPNs, TLS, certificates and CAs, …

Writing text that is version-controlled and readable, often in Markdown with automatic conversion to other formats. I even built an artist’s portfolio using Pandoc templates and some shell script. A static site, with just a little Javascript for gallery navigation.

I like to see development as a craft. As a practitioner of this craft, I know the importance of being familiar with my tools. I get a lot of things done on the command-line, which leans itself well to automation.

Projects ¶

Selection of community projects that I’m involved in.

age-plugin-tkey

I’ve begun an implementation of a plugin for Filippo Valsorda’s encryption tool age for using a TKey as the identity. It uses a new device app for doing X25519 (key exchange on Curve25519, using Monocypher). One goal is to provide a stable, general purpose device app for X25519. Note that this is work in progress, the tkey-device-x25519 app in particular is likely to change, which will cause the identity to change.

Fruktkartan.se

In the autumn of 2019, I took the initiative to revive and rebuild Fruktkartan (“The Fruit Map”), which is a collaborative map of fruit trees on the common lands which are free to harvest. Built using Leaflet, Vuejs, Nodejs, PostgreSQL with PostGIS, and some Python. The development is a collaborative effort. The new website was launched in 2020.

Mumla

Since 2020 I’m maintaining an Android app for Mumble, the free and open-source voice conference system. It’s a fork of the old Plumble, which had been abandoned by the author a few years earlier. Written in Java, embeds some native audio libraries written C, uses Protocol Buffers for server communication.

ntsclient

A Go implementation of Network Time Security (NTS) extensions for the Network Time Protocol (NTPv4). Beginning in 2019, I’m hacking on this client with some friends. Trying to keep it inter-operating with other implementations as the IETF draft evolves. NTP, now also secure! And hopefully immune to abuse for amplifying of DDoS attacks. Thanks to rough consensus and running code, the NTS draft eventually became RFC 8915.

Pjodd.se

Beginning in 2017, I was helping out to run a mesh-network that provides free WLAN Internet-access on the streets of Malmö. The firmware used was Gluon/OpenWrt. To help us build the network, I built a tool using D3js for graphing the mesh connections. I was also looking at metrics collection and visualization using tools like Prometheus and Grafana. The project is now defunct.