This is not a review, and I don't hand out stars either. It is part of my annotated reading list. Whatever first comes to mind when I pick up the book. More about it in this blog post. The English text is a translation made with an LLM, which I check and revise myself.
written on November 13, 2026, read 1992
In my bubble1 back then, it was the reading recommendation: you absolutely had to read “Cuckoo’s Egg” by Clifford Stoll. Stoll is quite an interesting figure. To this day, he owes his fame to a security incident in an internet that was still in its infancy. Later, of all things (or perhaps precisely because of it), he became an outspoken critic of networking.
By way of explanation: Clifford Stoll noticed a tiny accounting discrepancy (75 US cents) and discovered that someone was active on a system who didn’t belong there. In his book, he tells the story of the “hunt” for this intruder – and of how the whole affair turned out to be rather bigger than a break-in into the system of a single research institute. I don’t want to give too much away. If you’re curious, read the book or consult the Wikipedia page.
I bought the book after finishing school2, a few months before I started university. That’s a good 34 years ago now. It’s a significant book for me. But that doesn’t mean I don’t have my problems with it.
When I first read the book, barely 20 years old, I was of course completely thrilled. It was one of the few books I knew in which my hobby was portrayed even remotely positively. Most things in that vein were either completely utopian, abysmally dystopian or simply ridiculous.
Not much has fundamentally changed since then. Just think of “Hackers”, “Sneakers”3, “Johnny Mnemonic” or, worst of all, “Swordfish”. It says a lot about Hollywood’s view of a profession when the good scenes are so few and far between.4
“The Cuckoo’s Egg”, on the other hand, actually described what would later shape much of my career: sinking your teeth into a problem until it’s solved.
So why don’t I see the book quite so positively today? Well, sinking your teeth in has its downsides too. You lose all sense of proportion.
First towards yourself. Hyperfocus isn’t just something you know from ADHD; you also know it from that itch at the back of your mind that’s always most annoying when you don’t understand something but believe you’re only moments away from the solution.
And you lose your sense of proportion towards others: in such moments, everything else is subordinated to the solution. That’s not a pleasant trait.
Seeing problems and wanting to solve them can eventually become an obsession. And that obsession is exactly what I see in this book today: the inability to let go. Always thinking further, always trying to uncover the next layer of a problem. Not being able to put a problem down until it’s solved.
Now, you could object: Stoll found the hacker in the end, he was proven right, and in this case the end may justify the means. True. Possibly.
But on the way there, from my point of view today, he came pretty close to vigilantism. He didn’t just help the law enforcement agencies; to a large extent he saw himself as a substitute for them, because in his view they weren’t pursuing the problem with enough vigour. That’s exactly the sense of proportion you have to keep an eye on when you’re about to go down a rabbit hole.
My rabbit holes are usually performance problems. There’s no danger of straying into law enforcement territory there. But the mechanisms inside me are the same. I know the thrill when the core of a problem suddenly reveals itself after hiding stubbornly behind other problems.
Perhaps it’s partly down to the profession. Stoll is actually an astronomer, and he tells of an exam situation that had nothing whatsoever to do with computer science. He was asked: “Why is the sky blue?” What sounds like a very simple question is, seen through the right lens, a veritable bottomless rabbit hole. A highly recursive “Why?”. Why is the sky blue? Why are 75 cents missing? Or in my case: where do the extra 0.2 ms per transaction come from?
In the end, the book is as much a story about a hacker hunt as it is about the inner life of the hunter.
Somewhere in my late thirties, I noticed this inability to let go in myself. And with that, my view of the book changed too. It increasingly became a mirror, and I didn’t like what I saw in it. Do I always have this reflex under control today? No. Not always. But almost.5
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That’s what the young people call it these days, I’m told. dodders off ↩
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The ISBN and links refer to a current edition, which I haven’t read myself. Mine is still the old one from the nineties of the last century, by now rather battered. keeps doddering ↩
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I’d like to defend this film, though: it’s unrealistic, but I quite enjoy watching it. Besides, it’s where I learned what a Winnebago is … ↩
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I still remember the excitement when a real nmap suddenly appeared in “The Matrix Reloaded”, complete with an exploit that was current at the time. Hollywood had actually been on a good path once before. You may smile at the premise and the tic-tac-toe in “WarGames”, but more than forty years ago that film already showed that suspense and a reasonably realistic view of computer security can go together. At some point, though, Hollywood took a wrong turn. ↩
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To quote the series “Billions”: “Bloodhound can’t help blood-hounding, but he’s all bark now.” ↩