Three steps to a life of success

1. Be born to the right parents
2. Nepo
3. Coast

Things written in times past

I used to write things for a previous employer's tech blog, but the old URLs may succumb to bitrot. These should work as long as Medium works:

The challenges of running a betting exchange (2016)

Notes on interviewing engineers (2016) -- This one was also picked up by a recruiter's blog.

DevOps is culture, not a title prefix (2017)

Security and Devops - a natural fit (2017)

Wait, what is my fleet doing (2018)

Hey, guess what? Your passwords have been compromised

Shields up on user information (2019)

Dedicated to Cause

UK government's refusal to negotiate with the NHS staff can only be taken as dedication to monarchy. They want to make sure that King Charles's coronation will be a once-in-a-lifetime experience for as many people as possible.

Audits explained

A pentest is like going to the GP for a check-up. An audit is like having a month-long colonoscopy.

Not your grandfather's MVC

This was perfectly predictable. CoPilot generates insecure code, as expected.

Machine Learning, the magic pixie dust of the past decade, is all about volume. And writing secure code is harder than writing insecure code. So by sheer volume there will be a lot more insecure code around.

Given that a lot of code in the wild is essentially a minimum viable copypaste from the highest scoring answer on StackOverflow, teaching the code generator model has obviously consumed a lot of insecure code. Since SO rewards speed, the answers that take the least time to write will receive most points.

Writing secure code takes more time and more space - so by the time someone submits an answer that considers security aspects, the person asking the question has already accepted (and ran with) the first and shortest working answer instead.

StackOverflow has redefined the MVC programming model. It now stands for Minimum Viable Copypaste.

Lusikoitavaa chiliä

Arvioitu valmistusaika: 1,5h

Muokattu Guardianin reseptistä

Ainekset

• Reilu 300g tuoreita chilejä
• 1kg hienosokeria
• Pektiiniä
• 400ml siideriviinietikkaa

Muut tarvikkeet

• Hillopurkkeja
• 5l kattila
• Soseutin

Esivalmistelut

Mittaa reilu 5g pektiiniä ja sekoita hienosokeriin.

Keitä purkit ja kannet erillisessä kattilassa. Ota syrjään ja pidä veden alla kunnes hillo on valmista.

Valmistus

Leikkaa chilien tyvet pois, halkaise ja poista siemenet sekä suurin osa valkoisesta lihasta.

Perattuna chilejä pitäisi olla noin 250g. Ei ole kovin tarkkaa. (Alkuperäisen reseptin mukaan 200g riittää mutta nyt lisätään vähän potkua ja makua.)

Pilko chilit sopivan pieniksi ja soseuta.

Laita aineet kattilaan:

• sokeri ja pektiini
• soseutettu chili
• etikka

Keitä ja sekoita noin 15m verran. Keitos saa kuohua ihan kunnolla.

Hillo on valmista kun se jähmettyy kylmälle lautaselle. Jos keittämistä jatkaa muutaman minuutin pitempään, tulos on gelatiinimaisempi.

Kaada hillo purkkeihin. Vie ensin joksikin aikaa huoneenlämpöön tai ulos jäähtymään, ja kun purkit eivät enää ole kuumia, siirrä jääkaappiin.

Säilytys

Pysyy hyvänä jääkaapissa jopa puolikin vuotta. Ellei lopu ensin.

SSH (Yubi)Key Authentication

SSH with private keys coming from secure hardware. What's not to like?

You've read the How-To. You've changed the pin with:

yubico-piv-tool -a change-pin

You're generating a resident key with:

ssh-keygen -t ed25519-sk -O resident -f ~/.ssh/yubi_ed255_key

After entering your pin, the above command breaks with "enrollment failed: invalid format". Surely you're doing something wrong? After a minute of head scratching, you try again, this time with:

ssh-keygen -vv -t ed25519-sk -O resident -f ~/.ssh/yubi_ed255_key

And are greeted with a confusing error. According to the error code (FIDO_ERR_PIN_NOT_SET) the resident key can not be generated because your YubiKey is not protected with a pin. But you've changed it already - what gives?

You've changed the PIN for the PIV application... which is different from the FIDO2 application.

Right idea, right PIN, wrong application?

Turns out you're missing the right tool. Get the correct one with:

${SUDO} apt install yubikey-manager

And then configure the FIDO2 application code with:

ykman fido access change-pin

Now you can rerun the command from above and generate a private key directly with the YubiKey.

(Update 2025-03-15: ykman fido command updated)

Things that work

The private key file, generated by the ssh-keygen command, can be nuked. It is after all a resident key, accessible directly from the YubiKey device. And you probably didn't add a keyphrase for it either.

So you can now load the private key into SSH agent, with:

ssh-add -K

You'll need to type in the PIN you set earlier.

... and a few that don't

The main problem with the above setup is that every use of the private key, even when loaded to the agent, requires to touch the magic button. To make things worse, the client doesn't show any hint what is needed, from a casual observer's point of view establishing the connection seems to hang.

This is okay for random logins, but breaks non-interactive workflows, and utterly messes up remote autocomplete. Touch the key one time too few, and the autocomplete never finishes. Touch it one time too many, and you've just vomited an OTP string to your terminal.

An ideal setup would allow the agent to authenticate without interaction for a configurable time, but so far this seems not to be supported.

Near-future experimentation

Documentation for ssh-keygen states that the resident key may be generated with the additional option -O no-touch-required to allow fully non-interactive use. At least at the time of writing, portable OpenSSH v8.4 does not appear to support the option, which may be for the best. Additionally, the public key requires special annotation for its entry in authorised_keys but even then it's not a good idea.

Because this option essentially would turn the YubiKey into a USB-attached SSH trust/identity dongle, it's far too dangerous to be used without other mitigations.

The missing hint

The bit about FIDO2 application for SSH client and the necessary command was found here.

Helpful two-liners

When changing the PIN/PUK codes, of course you want the new codes to be random. A really easy way to generate them is with python. Like this:

% python3

import secrets

secrets.randbelow(10**6) # for PIN

secrets.randbelow(10**8) # for PUK

Be honest

Planning to travel to visit your family in these plague-ridden times, you're really saying:

"I miss my family so much they will see me if it's the last thing they do."

Page from an undated journal

Daddy's crying. Mommy has a black eye. Little sister's hiding under her bed.

Yep, it's christmas.

Misunderstood Indexing

Holding the number-one spot on Corruption Perceptions Index tells nothing about how well a country is doing.

It merely highlights how bad the situation is even for the runner-up.