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An interesting Tailscale + Docker gotcha

2026-01-29T00:00:00Z

As I’ve written about before, I use Tailscale for a lot of things. I thought I had it set up in a reasonably secure manner, but I recently noticed a problem.

I use Tailscale’s ACLs to limit what each node can access, based on the tags I apply to it. So an app node can’t access anything via Tailscale, while an integration or server node can access things tagged with either app or integration. This is expressed pretty simply in the Tailscale ACL JSON:

{
	"tagOwners": {
		// Servers that can be SSH'd into
		"tag:server": [],
		// Applications that are exposed on tailscale but never connect out
		"tag:app": [],
		// Things which talk to other services over tailscale (connecting to apps etc)
		"tag:integration": [],
	},
	"grants": [
		{
			// Users can access everything
			"src": ["autogroup:member"],
			"dst": ["*"],
			"ip":  ["*"],
		},
		{
			// Servers and integrations can access integrations and apps
			"src": ["tag:server", "tag:integration"],
			"dst": ["tag:integration", "tag:app"],
			"ip":  ["*"],
		},
	],
}

Over the past week I’ve been setting up a private Forgejo instance behind Tailscale, complete with an actions runner that runs things using a docker-in-docker container. I didn’t want the runner knowing anything about Tailscale, so I had it configured to speak to Forgejo direct over HTTP (forgejo:3000) instead of using full Tailscale HTTPS URL that I use when accessing it (http://git.example-net.ts.net/)¹.

Everything was going fine, until I forgot to do that translation… and it worked. My Forgejo action runners could access anything on my tailnet. I run several things on Tailscale that just have authentication turned off, on the basis that only authorised devices can access them. Things like the admin interface for this website. I definitely didn’t intend for any workflow I run on my git server to have access to edit my website!

This wasn’t just limited to Forgejo, either. Any docker container I was running could access the tailnet. In hindsight it’s fairly obvious why: the host is running Tailscale, connected as a node tagged with my server tag. That creates a tailscale0 interface, and automagically sets up iptables rules to route Tailscale traffic over the interface. Docker also automagically sets up iptables rules to bridge traffic, and apparently these two sets of rules interact in such a way that traffic from Docker containers is allowed to route via the tailscale0 interface.

I say it’s fairly obvious in hindsight — there’s no reason why Docker would special case any particular host interface after all — but it still feels pretty surprising. Because both bits of software inject their own iptables rules, I never really had a good mental model for how they interact. The host Tailscale node was a completely separate building block to Docker. It would be a pain to use either of them if they didn’t do these rules, but it’s also one of the reasons I don’t really like “magical” things².

There are lots of ways to fix this, but none of them feel particularly great. You can configure both Tailscale and Docker to not automatically fiddle with iptables and handle the rules yourself, but I really hate dealing with iptables³. As a stopgap I did hold my nose and add some iptables rules to drop traffic to the tailscale0 interface if it originated from the IP ranges that Docker was configured to use:

iptables -I DOCKER-USER -s 192.168.0.0/16 -o tailscale0 -j DROP
iptables -I DOCKER-USER -s 172.17.0.0/12 -o tailscale0 -j DROP

The DOCKER-USER chain is a nice little escape hatch; it comes before the main auto-generated DOCKER chain, and Docker leaves the rules in it alone.

So I added these rules, and felt pretty good about myself, and then… everything started breaking in weird ways. After some debugging I realised the problem was DNS⁴. The server’s DNS resolver is 100.100.100.100, a special Tailscale address. This is so that it can resolve tailnet hostnames via MagicDNS (and so I don’t have to configure my custom DNS servers manually on each device; Tailscale does it for me). My new iptables rules inadvertently dropped all the DNS packets coming from docker containers. D’oh.

Obviously the solution here is to double down and add MORE iptables rules:

iptables -I DOCKER-USER -s 192.168.0.0/16 -d 100.100.100.100 -o tailscale0 -j ACCEPT
iptables -I DOCKER-USER -s 172.17.0.0/12 -d 100.100.100.100 -o tailscale0 -j ACCEPT

This got DNS working again, but it all feels a bit gross. Not least because to actually make these persist you need to use iptables-save, and then you also get all the rules that both Docker and Tailscale have inserted. I came across a script to filter out the Docker ones, but… yuck⁵.

I realised a cleaner idea might just be to lock down what server tagged nodes could access within Tailscale itself. That way I can avoid touching iptables at all. It’s handy to be able to curl services from the host when debugging, but it’s not really necessary. So I removed that access, and… stuff broke again. I’m using my Forgejo instance as a registry for some of the docker images I run, so the docker daemon needs to be able to reach it. I ended up making a new tag for infrastructure, which can be accessed from server devices. This does still allow all the docker containers to reach Forgejo, but I already have it set up with appropriate access controls and public/private repository splits. Forgejo is a service designed to run publicly, so this seems a reasonable trade-off for convenience. I used the tests feature of Tailscale’s ACL config to make sure I’d got the rules right:

{
	"tests": [
		{
			// Servers can only access infrastructure
			"src":   "tag:server",
			"proto": "tcp",
			"allow": [
				"tag:infrastructure:8080",
			],
			"deny": [
				"100.84.16.43:8080",
				"me@example.com:8080",
				"tag:server:8080",
				"tag:app:8080",
				"tag:integration:8080",
			],
		},
	],
}

The whole situation still feels a bit messy. If I ever get around to switching to nftables I might loop back and manually craft some rules for routing traffic, instead of leaving Tailscale and Docker to do their own thing.

I discovered later on that logging into the container registry at forgejo:3000 actually issued a redirect to https://git.example-net.ts.net/ so this was all basically for naught… ↩︎
I didn’t use Tailscale’s MagicDNS for a long time just because the word “magic” put me off. Only when I eventually got around to learning how it worked, and seeing that it wasn’t really that magical under the hood, did I change my mind. ↩︎
nftables seems far better in lots of ways, but I can’t really be bothered migrating. Maybe next time I reimage the server for whatever reason… ↩︎
It’s always DNS… ↩︎
Again, nftables would almost certainly help here. It actually has (gasp) configuration files. But again, I really didn’t want to spend the time migrating. ↩︎

Avoiding the Consequences of Dumb Laws with Tailscale

2025-09-30T00:00:00Z

More and more sites are implementing privacy-invading age checks or just completely blocking the UK thanks to the Online Safety Act.

Protecting kids from some content online is certainly a noble goal, but the asinine guidance from Ofcom, threats of absolutely disproportionate fines, and the stupidly broad categories of content have resulted in companies just giving up or going through a tick-box exercise that offers very little protection but lots of inconvenience and a complete invasion of privacy.

Instead of uploading my ID to some third party company, I’ve taken to proxying my traffic through to a country that doesn’t have such stupid laws. Thankfully, Tailscale makes this really easy. I’ve discussed how I use Tailscale before, but not really covered app connectors. I find Tailscale’s description of these pretty confusing, but they basically amount to automatic, DNS-based subnet routing configurations (or, to put it another way, a per-website exit node). You can safely ignore all references to ‘SaaS apps’ in their docs.

I create a custom app connector, and give it the domains to be included:

App configuration in the Tailscale admin console

Tailscale then magically resolves those domains, and has the ‘connector’ advertise routes for them. Any client that accepts routes will start sending requests to the connector, which passes them onto the Internet at large. Any other traffic is left alone, unlike when you use an exit node.

The special bit here is how you can specify wildcard domains. Tailscale proxies the DNS requests from clients (so it can inject responses for nodes on your tailnet), which means it can dynamically update the routes as you resolve new domains. I tried to set this up more manually, and quickly came unstuck: despite using the same DNS servers, my server and my desktop would get different responses for the same query as it varied by geography. Trying to get the full set of IPs (and keeping them updated) would have been a nightmare. Tailscale expanding the wildcards nicely sidesteps all of that.

At first I was just proxying the traffic to one of my servers, but just today I added a new connector for Imgur and found I was still blocked, just for different reasons. They not only block my entire country but also a load of known datacenter IP ranges. Hmph. I fixed this by hacking up a new side project: tsv. It’s a simple Go app that accepts traffic from the tailnet (advertising itself as both an app connector and an exit node), and passes it on to another VPN.

There are lots of other ways you could accomplish this, but this makes it so all my devices can still access services without any additional configuration. As long as Tailscale is installed, the Internet will still work as it’s meant to, without all the nonsense. If I come across a site that doesn’t work, adding it is trivial: I just make a new app connector in Tailscale.

Obvious disclaimer: the laws in the UK are binding on the service providers, not the end user. Doing this sort of thing in other countries might be illegal. I don’t know; do your own research! Also all of this is a workaround for something that should be fixed at a legislative level, but I’m not holding my breath.

Fixing a loud PSU fan without dying

2025-07-30T00:00:00Z

Three months after I built my new computer, it started annoying me. There would occasionally be a noise that sounded like a fan was catching on a cable, but there weren’t any loose cables to be a problem. Over the course of a few weeks, the sound got progressively worse to the extent that I didn’t want to use the computer without headphones on. I measured the sound at 63 dB, which is about the sound of someone talking. That may not sound terrible, but it’s a constant, nasty noise coming from something that sits about 40cm from my head.

After some investigating¹, I identified the PSU fan as the culprit. I have a Cooler Master V750 SFX, which is not super high-end, but wasn’t cheap, either. It shouldn’t be developing issues after three months. Thankfully, it comes with a ten-year warranty, so it should be easy to get sorted, right?

Warranty woes

I looked at Cooler Master’s warranty, and for issues within the first two years you have to deal with the retailer. That would be Amazon in my case. So I looked at Amazon’s information on warranty issues. Their policy is that if it’s more than 30 days since purchase, you have to send it off to a third-party repair center and wait for them to diagnose and try to repair it. Here’s the kicker:

Usually repairs take up to 20 business days (including delivery time), but could take slightly longer

I use the computer for work, have upcoming LAN parties to go to, and generally can’t do without it for an entire month. That’s assuming they reproduce the issue: the PSU fan only turns on when it reaches a certain temperature, so if you just plug it in briefly it won’t exhibit any symptoms.

If I was going to do a warranty return, I’d need to buy a new PSU first to use while this one was away. If I’m spending £100+ on a PSU, then I’d be getting a better one that doesn’t have known issues with the fans. So when the Cooler Master eventually got returned I’d have no use for it. What a waste.

So the warranty is about as much use as a chocolate teapot. Good to know, I guess. If I wanted decent service, I should have probably used a real retailer, not Amazon. Lesson learnt.

Doing some research

If the warranty is useless to me, maybe I should just void it and try to fix it myself. I did some research online. Most of the results went like this:

if you’re not a trained professional you should not be opening up your PSU at all. There’s a lot of current that goes through it which will seriously hurt/main/kill you

it’s time consuming and potentially dangerous

or some other variety of doom and gloom. There were some actually useful results sprinkled in, though. A post on the smallformfactor.net forums details someone swapping out the fan on the 850W version of the same power supply because it was too noisy. It looks like the fan connector in the PSU is a two-pin connector, and they just used an off-the-shelf adapter to convert the standard four-pin case fan connector. It sounded a bit annoying to make it all fit, though.

A similar post on reddit showed basically the same upgrade, but identified the connector as a 2.54mm JST-XH. They crimped their own connector on, which feels a lot better than using a bulky connector. I do have a crimping set for JST connectors, but I absolutely hate doing them because they’re so fiddly and annoying. I’m not sure if I trust one of my crimps inside a power supply, either.

Looking at the pictures in those posts, I identified the fan as an Ong Hua HA9215VH12FD-F00. I searched to see if I could see any specifications for it. I couldn’t. But what I did get back as my first result was another Reddit post, this one titled “Getting rid of a HA9215SH12FD-F00 fan from your PSU”. It says something about the quality of a component when the first result is a post about getting rid of it because it’s annoying².

All of these mods seemed easy enough, and I’m reasonably confident in my ability to both discharge and avoid touching capacitors, so I probably wouldn’t die. I ordered a Noctua NF-A9x14 fan and some pre-made JST-XH connectors and waited for them to arrive.

Upgrade time

The replacement parts arrived one evening, so when I turned the computer off for the night I unplugged it from the mains, held the power button down for a while, and left it overnight for good measure. The next morning I popped open the case, disconnected and removed the PSU, gleefully tore the “warranty void if removed” sticker off, and opened it up.

Removing the fan was simple: unplug the JST connector and undo the screws holding it to the outer panel. I confirmed that my JST connectors were the right size, then started surgery on the Noctua fan. I carefully removed the heatshrink, cut off the normal fan connector, and separated out the four wires. A quick check of their FAQ confirmed the wiring colours: black was ground, yellow +12V, and blue and green used for speed control (which we’re not using in this instance). I clipped the blue and green wires off near the hub so they wouldn’t be in the way, then cut the yellow and black wires down to length, and attached the JST connector with a solder seal:

Old fan, new fan, burnt mouse mat

In the process I discovered my mouse mat doesn’t like being hit with a heat gun. Whoops. The solder seals are great: the solder in the center melts to form an electrical connection, the parts at the end grip the cable to provide mechanical strength, and the whole thing acts like heatshrink and keeps the connection insulated. A lot less fiddly than crimping JST connectors, and a lot smaller and cheaper than an adapter.

I installed the fan and reassembled the PSU. Then undid it all and tried again, as apparently the face the fan mounts to isn’t quite symmetrical and I’d installed the fan upside down. Connected everything back up, plugged the computer in, booted it up, and… nothing. The PSU doesn’t actually power the fan until it hits a certain temperature. I figured putting it under load would probably heat it up, so ran a graphics benchmark a few times. Eventually the fan spun up. Huzzah.

Soon the entire computer will be beige and brown

Peace at last

I measured the sound of the new fan: 43 dB. That’s a decrease of 20 dB. Due to the weird logarithmic properties of the dB scale that no one understands, that means it sounds about 4 times quieter to human ears. Big improvement!

It’s worth pointing out this isn’t a straight one-to-one upgrade. I don’t know the specs of the old fan in terms of airflow, and I’m just assuming that the Noctua will be good enough by virtue of being a decent fan. They also behave slightly differently as the power ramps up: the stock fan starts spinning at a lower voltage than the Noctua, which needs around 7V to get started properly³. I don’t think this will be an issue, as it’s effectively just putting a small step at the lower end of the fan curve. It might shorten the overall lifespan of the PSU, but from my point of view it failed after four months, so any extra time is a bonus.

I recorded some before/after audio, so you can hear the difference. I think there’s some amount of volume normalisation going on, so it’s not quite as stark a difference as in person, but it’s still noticeable.

Audio sample from the old fan

Audio sample from the new fan

And if you couldn’t hear it, here’s a visual representation:

Side-by-side comparison of the audio clips

The whole upgrade took about an hour (less time than writing this post about it!), and I even managed to avoid killing myself.

Opening the case and sticking my ear near to various components. High-tech stuff. ↩︎
On closer inspection it’s actually a slightly different model — there’s an S not a V in the middle there — but I’m going to assume that doesn’t change much on the quality/noise front. ↩︎
It then keeps spinning down to about 5V or so, it just needs enough power to initially get started. ↩︎

How I use Tailscale

2025-06-25T00:00:00Z

The Tailscale logo

I’ve been using Tailscale for around four years to connect my disparate devices, servers and apps together. I wanted to talk a bit about how I use it, some cool features you might not know about, and some stumbling blocks I encountered.

I’m not sure Tailscale needs an introduction for the likely audience of this blog, but I’ll give one anyway. Tailscale is basically a WireGuard¹ orchestration service, with lots of nice features sprinkled on top. It’s a subscription product, but it has an insanely generous free tier that covers basically anything you’d ever want to do as an individual. They also open source all their client software, and there’s a third party control server implementation called Headscale if you want to avoid the hosted system entirely.

Basic connectivity

At its core, Tailscale lets you easily connect from one device to another, even if they’re not directly exposed to the Internet. You install the Tailscale client wherever you like (on your phone, computer, servers, Raspberry Pi, etc), authenticate the machine with the control server, and it can then talk to all the other machines on the tailnet using their private Tailscale IP addresses.

That isn’t anything revolutionary: it’s the basic premise behind VPNs. But Tailscale makes it so easy. You don’t have to bother with any networking configuration. You don’t have to distribute keys. You just install the client², and login.

For example, my home automation service runs on a Raspberry Pi that sits behind two different routers. I installed Tailscale on it³, logged in, and immediately I could SSH into it from my computer or my phone even when they’re on different networks.

Speaking of SSH, Tailscale has special support for it whereby it handles any incoming connection to port 22 from the Tailscale network, and deals with authentication itself. No public keys or passwords: if you’re logged into Tailscale you can be logged into the machine. This is particularly handy when you SSH from a phone, as proper credential management is a bit of a nightmare there.

Exposing entire machines is just the start, though. If you run multiple services on the machine you need to remember which port they’re all on. Yuck. Instead, you can expose individual services as their own node on a tailnet. There are lots of options for doing so: there’s an official Docker image, a Go library, and many third-party tools (such as my own Centauri and tsp).

Not just a VPN

Exposing individual services wouldn’t be much use if you still had to remember their IP addresses. For a long time I manually added DNS entries for Tailscale nodes, allowing me to connect to http://grafana/ instead of http://100.73.190.100. Recently I switched to Tailscale’s MagicDNS, though, which takes care of that for you. Every machine on the tailnet gets an automatic DNS entry based on its name.

I initially shied off of this because it changes the DNS resolver on every machine it’s installed on, and it all seemed a bit too “magic” for me⁴. I got fed up with manually adding DNS entries though, so I spent a bit of time learning about it and got over my knee-jerk “what on earth is going on?!” reaction. The DNS controls also let you force a specific upstream DNS server. I use NextDNS everywhere, so having Tailscale automatically configure this for me on all my devices was a bonus⁵.

As well as the short names, you can resolve nodes on the tailnet using a slightly longer form: machine.your-tailnet.ts.net. The “your-tailnet” bit is randomly generated, and you can reroll it in the control panel to find a fun one. But why waste time say lot word, when few word do trick? Because Tailscale can make these addresses globally routable, and issue TLS certs for them too.

Say you’re developing something on your local machine, and want to get feedback from someone. You can use Tailscale’s “funnel” feature to expose it publicly:

tailscale funnel 127.0.0.1:8080

With no other options, this will expose the service over HTTPS on port 443. You can then invite people to visit https://machine.your-tailnet.ts.net and they’ll connect through to port 8080 on your machine. They don’t even need Tailscale installed. I don’t use this terribly often, but it’s a great quality-of-life improvement on the occasions I do want to share something.

Tailscale also has a “serve” command, which does much the same but only exposes it over your tailnet. This is how you’d use the Tailscale Docker image to expose a normal service onto your tailnet, but it’s also useful for similar development scenarios. Occasionally I’ll want to test something on my phone, and rather than make sure it’s connected to the right Wi-Fi network, recompiling the app to not bind to localhost, figuring out my machine’s IP, and so on, and so forth, I just run tailscale serve and access it over Tailscale.

Authentication, two ways

One of my minor frustrations with Tailscale was how cumbersome the authentication process was. I logged in using GitHub, and every time I tried to login to Tailscale, I had to bounce through the GitHub OAuth flow and then select which organisation I wanted to use. Even if I was logged in to GitHub, it still shows the permission page every time. It’s not a dealbreaker, but it’s definitely not smooth. This is what it looks like:

Logging in to Tailscale with a GitHub account

Tailscale have since added the ability to sign in with a custom OIDC provider, so I set up a KeyCloak instance, and my login flow now looks like this:

Logging in to Tailscale with KeyCloak as an OIDC provider

It’s a significantly shorter flow, and because KeyCloak is entirely under my control I can configure how long I stay logged in for. It also reduces my reliance on third parties: if GitHub goes down, or decides to ban my account⁶ or something, I can still access Tailscale.

That’s how you log in to Tailscale, but Tailscale can also assist with logging in to other services. If you connect to a HTTP service over Tailscale, it will add in the following headers:

Tailscale-User-Login: alice@example.com
Tailscale-User-Name: Alice Smith
Tailscale-User-Profile-Pic: https://example.com/photo.jpg

A lot of software has support for accepting login credentials provided by a reverse proxy, which is basically what’s happening here. For example, I run a Grafana instance that’s only exposed over Tailscale. Its config (set in environment variables) is:

GF_USERS_AUTO_ASSIGN_ORG: "true"
GF_USERS_AUTO_ASSIGN_ORG_ROLE: "Admin"
GF_AUTH_PROXY_ENABLED: "true"
GF_AUTH_PROXY_HEADER_NAME: "Tailscale-User-Login"
GF_AUTH_PROXY_HEADER_PROPERTY: "email"
GF_AUTH_PROXY_AUTO_SIGN_UP: "true"

So anyone who presents a Tailscale-User-Login header gets an admin account created with that as their e-mail address. It’s super convenient, but obviously make sure it’s only exposed via Tailscale if you do that!

Other services I run that support this include Miniflux (an RSS reader), Jelu (a book tracker), Linkding (a bookmark manager), and Seafile (a file storage system). If you’re hosting something yourself, look out for “proxy auth” or “remote users” in the documentation or configuration. It’s amazingly convenient to be able to access things without entering credentials.

ACLs, tags and mistakes

For a long time I didn’t bother with any kind of ACLs within my Tailscale network. Every machine could access every other machine. Then one day a thought hit me. The default Tailscale SSH config re-prompts you for user authentication, but I’d disabled that by tweaking the config… That means anyone with access to any of my machines (or who managed to get Tailscale credentials out of one of my apps) would be able to SSH into anywhere else on my network. Even as root! Compromising a small bit of my network would immediately lead to a complete take-over. What’s the point in defence-in-depth if you roll out a red carpet over the drawbridge for any attackers?

The first and most obvious fix for this was to restrict root access over SSH. I changed my Tailscale ACL to prompt for reauthentication for root access, but still allow regular SSH unprompted:

{
  "ssh": [
    {
      "action": "accept",
      "src":    ["autogroup:member"],
      "dst":    ["autogroup:self"],
      "users":  ["autogroup:nonroot"],
    },
    {
      "action": "check",
      "src":    ["autogroup:member"],
      "dst":    ["autogroup:self"],
      "users":  ["root"],
    },
  ],
}

This still didn’t sit right with me, though. Why should a random webserver be able to (theoretically) SSH into my desktop computer unchallenged? Tailscale allows you to do more advanced ACLs by applying tags to devices. I dutifully created a bunch of tags, and went through and tagged every device: user, server, app, container, and so on. This, it turns out, was a mistake. I could no longer SSH to anywhere. If I’d read the docs properly, I might have noticed how they describe tags:

Tailscale tags are how you authenticate and identify non-user devices, such as servers and ephemeral nodes. They serve two primary purposes: to provide an identity to non-user devices and to let you manage access control policies based on purpose.

By applying a nice user tag to all of my devices (computer, phone, tablet and so on), I’d effectively removed my own identity from them. They no longer counted for the autogroup:member source in the SSH config. Whoops. And it’s not easy to fix either:

You cannot remove all tags from a device. A device with a tag-based identity must have at least one tag.

So I’d have to remove all the affected devices, then re-add them. At the time I wanted to roll back all the tags, which would mean reconnecting dozens of nodes to the Tailnet. I did end up doing that, but I also took it as an opportunity to switch to KeyCloak as I mentioned earlier. Setting everything up again was a bit less painful when it wasn’t just correcting a dumb mistake.

I now have a much more sensible tag setup: servers are tagged server, apps are tagged app, and a few special apps are tagged integration. I then use Tailscale’s grants to limit access within the tailnet:

{
  "grants": [
    {
      // Users can access everything
      "src": ["autogroup:member"],
      "dst": ["*"],
      "ip":  ["*"],
    },
    {
      // Servers and integrations can access integrations and apps
      "src": ["tag:server", "tag:integration"],
      "dst": ["tag:integration", "tag:app"],
      "ip":  ["*"],
    },
  ],
}

This stops anyone but a user device from accessing servers, and stops plain apps from accessing anything at all. So for example my Grafana instance is tagged as an app; it doesn’t connect out over Tailscale for anything, it only exposes its interface over Tailscale. My home automation software is tagged as an integration, as it reaches out to other services over Tailscale (e.g., to push metrics it receives from devices).

You could go even further and limit which specific machines talk to which others, but I think this tier system sets reasonable boundaries for my use without getting too much in the way.

Even more

There are lots of other cool features offered by Tailscale that I’ve not covered: exit nodes (allowing you to route normal Internet traffic over Tailscale; very handy when you’re behind a router you don’t trust, or if you want to appear as being in another country for totally legitimate reasons); Tailscale lock (a system where existing nodes have to verify any new ones, guarding against both unauthorised access and Tailscale themselves inserting nodes into your network); file sharing, and more I’ve probably forgotten.

As I mentioned before, an awful lot is available on the free personal plan. It’s definitely worth checking out if you manage servers, or self-host anything. I can’t imagine going back to managing servers and private apps without Tailscale, and I’m excited to see what else they do going forward.

If you’re not familiar with it, WireGuard is a modern VPN included in the Linux kernel. It’s basically the only VPN that isn’t terrible. ↩︎
They have installation instructions and packaged versions of the client for just about every device you can imagine: Windows, Mac, every major Linux distribution, iOS, Android, etc, etc ↩︎
They even have an apt repository specifically for raspbian builds, so it’s super easy. ↩︎
Lots of people seem to treat “magic” as a good thing in software. I think it’s the absolutely opposite. I want to know how something works, not for it to be inscrutable! ↩︎
This is entirely optional, of course, you can just let each device do their own thing as well. ↩︎
I don’t think this is likely, but it’s one of my biggest concerns about using “social” logins. More-or-less all of these services can arbitrarily ban you with no recourse; why would you trust them as keyholders to other things? ↩︎

Building a new Computer

2025-06-03T00:00:00Z

The finished PC. Cat pen for scale.

I recently¹ built a new computer, after exclusively using a laptop for three years. It’s also the first time I’ve departed from the usual combo of an Intel CPU and Nvidia GPU.

While the form factor of a laptop did make it amazingly handy for travelling and attending LAN events, it was starting to show its age and there was basically no sane upgrade path. The main problem was its 3060 mobile graphics card, which was okay for the first few years and then slowly descended into painful. At the time, the (fairly disappointing) 50-series had just been released, but hadn’t yet made it into laptops. Nvidia had stopped production on the 40-series beforehand, so there also weren’t any compelling options there, either.

That’s not to say there were no laptops at all that I could have upgraded to. There were. Just not really any that ticked all of my perfectly normal boxes like “run Linux”, “have at least 64GB of ram”, and “run modern games well”. Having to upgrade the entire system just because the graphics card was showing its age was a bit of a drag, too. So back to the land of desktop computers I went!

To try to preserve some of that convenience, I opted for a small form factor (SFF) case. The computer and all the accessories can fit inside a hand-luggage-sized flight case. More on that later, though.

Components, Choices, and Cramming

So what, exactly, is in this computer? The case is a Fractal Design Terra, which is a lovely little 10.4L case². My last desktop PC was a normal-sized Fractal Design case, which I liked a lot, and it seems like they’ve upped their game since then. The Terra is both pleasant to look at (just look at that wooden panel!), and a breeze to work in. The sides and top are fully and easily removable, giving you great access to everything inside³. I expected an SFF build to be fiddly, but the case made it feel about the same as a normal full-sized build⁴.

The case with sides and top off, and wires everywhere in desperate need of management.

Another nice feature of the case is the movable spine. I think this is relatively common in SFF cases, but it was new to me. You mount the graphics card on one side of a metal divider, and everything else on the other. The divider (or spine) can be moved side-to-side depending on what exactly you’re putting in the case.

As I mentioned earlier, this was my first departure from the Intel + Nvidia bandwagon. Nvidia’s 50 series was underwhelming, and Intel managed to put out a generation of chips that literally fried themselves. It seemed like a good time to try out AMD’s offering! I went for the newly released Radeon RX 9070XT graphics card, and a Ryzen 7 9800X3D processor⁵. The processor has a Thermalright AXP90 X47 Full heatsink on top of it, with a Noctua NF-A9 fan on top of that.

The motherboard is a Gigabyte B850I Aorus Pro, and it hosts 2 32GB Corsair Vengeance RAM modules, and a 2TB Crucial T705 NVMe drive. Powering it all is a Cooler Master V750 SFX. The PSU is modular to reduce the number of wires that need to be fitted in, but they’re still pretty big and bulky. I’m tempted by custom cables but they’re rather pricey, and you can’t actually see inside with the sides closed…

With the diminutive size of the case and all the components crammed in, there’s actually no room left over for case fans. The PSU, GPU and CPU all have fans attached, but that’s it. There are stories online of people having heat issues, but thankfully everything seems pretty happy in my setup. The components all draw in air from the sides, and the hot air passively vents out the top. If I keep the CPU under maximum load for a while then it starts to thermal throttle slightly, but the only time I’ve actually managed that is when compiling a kernel. Why was I compiling a kernel, you ask? Well, we’ll come to that.

But does it Linux?

I didn’t go into this build completely blind. I did a bit of reading and chatting, and it sounded like AMD drivers were pretty good on Linux these days. I didn’t check specifically if any of the components were supported.

The 9070XT was released on the 6th of March. I built my PC on the 26th of March. The first version of Mesa (the 3D graphics lib) that was generally stable with 9070XT cards landed in Arch on the 20th of March. If I did the build just one week earlier, I would’ve had a much less fun experience.

It still wasn’t quite perfectly smooth, though. When playing games I’d occasionally have issues. In some cases the screen just went blank and came back after switching windows, but in others the graphics drivers couldn’t recover and the PC needed rebooting. Fortunately the drivers are open source, and they have a public issue tracker hosted by the Freedesktop project. Searching through the issues, I found they’d already been reported (by another Arch user, of course), and there were various suggestions for work-arounds, as well as lots of work trying to reproduce the issue.

Within a week, an AMD developer had posted a set of patches that might address the issues, and asked people to test them. That’s fortunately pretty easy on Arch: you just clone the repository containing the PKGBUILD file, drop in the patches, and update the checksums for them. Then you start compiling, realise you didn’t tell it to use more than one CPU core, abort it, and start again but this time running on all cylinders. Soon enough I was running a patched 6.14 kernel and the problems stopped completely. Others reported similar outcomes, and the patches worked their way into the kernel proper.

I spent a few weeks having to compile a custom kernel every time I accidentally updated it (I should’ve just stopped pacman from touching the kernel for a bit…), then one day the patches didn’t apply because they’d been merged upstream. Since then everything has been perfect.

A friend commented that “this wouldn’t happen with Nvidia”. They meant it negatively, but I wholeheartedly agree! Maybe Nvidia have fewer launch bugs than AMD, but you absolutely wouldn’t be able to talk to their driver engineers on a public bug tracker, and get access to test patches that fix your issue. I’ll happily take a few bugs in exchange for a company that operates openly in a way consistent with the rest of the Linux community.

But does it travel?

Travel mode, engage!

So the computer works fine at home, but how do I get it to other places? I just shoved a laptop in a backpack⁶, but you can’t quite do that with a PC even one this size. I’d seen a few people at LANs who packed everything in flight cases, but they always seemed a bit unwieldy. Doing some research, though, I found that I’d just be able to squeeze everything into a flight case sized to be taken onto a plane as cabin baggage.

Peli (or Pelican in the US) are the most well known maker of flight cases, but I chose to go with Nanuk instead. Spec-wise they’re fairly similar. Nanuk are a bit cheaper. The killer difference for me, though, is that Nanuk publish STEP files of their cases. As someone with a 3D printer, giving me CAD models of things so that I can easily mod them is definitely a way to win my favour.

After lots of measuring and thinking and modelling I came up with an arrangement where everything could fit snugly into the case. The case has cutouts for the wheels and handles, which constrain what can go where. I ended up wanting the computer at the handle-end of the case to make best use of space, but that means it needs something to take its weight when the case is vertical. The solution was, of course, 3D printing.

Using the STEP files from Nanuk I designed an insert that spans across the case, with screw holes that line up with the ones in the flight case. I wasn’t sure it would be able to take the weight like that, so I also added in some supports in the other direction (running down to the bottom of the case, if it’s stood up). I ended up printing it in three parts, and it came out perfectly first time. I can’t emphasise how nice it is having CAD models instead of having to measure and guess at things.

With the support in place, I focused on cushioning the computer. I opted for 10mm thick EVA foam as it’s easy to obtain and work with, and doesn’t take up too much room. I used contact adhesive to glue the foam directly to the case and the 3D printed divider. There’s a piece that goes between the computer and the keyboard, so I printed some little 3D supports to hold that more firmly in place, and stuck those in with contact adhesive as well.

So how does it all hold up? It’s been to one LAN event so far, and it’s great. I think the flight case might actually be easier to carry than hefting a heavy backpack: the handles are sturdy and comfortable, and it has chunky wheels for pulling it around. It’s also actually easier to get everything set up when you can see it all laid out in the flight case and pull out what you need, and then the case can be tucked away out the way for the duration of the event.

Recently-ish. It may or may not have taken me a few months to get around to writing this post. ↩︎
Using litres to measure computer cases always feels wrong. Those are the units we use for water. Don’t put them near the computers! ↩︎
The case also has holes to put security screws in to stop all of these nice easily removable parts from being removable. Very handy when you’re leaving it unattended at a LAN. ↩︎
Which for me means it was good fun for about an hour, and then I got fed up and just wanted it to be done already. ↩︎
Three months in and I still can’t remember these random strings of numbers. Someone even explained the versioning scheme to me. ↩︎
Along with a portable monitor, mouse, keyboard, headset, mouse mat, kensington lock, power supply, cables, and controller. It was a heavy bag. ↩︎