Ask HN: What's your proudest hack?

I moved back to Texas from college without any job prospects and found myself living in my car, relying on Walmart Wi-Fi for internet access.

So, I resorted to a few low-quality hacks.

The first was a QR Code parking app. It worked by just placing a qr code on public parking meters. I marked up the parking from like from 50 cents to a dollar. I kept 50 cents and payed for the parking through the official app with mitmproxy. Someone eventually reported it.

I had to ask my dad for help reimbursing the city—which he was not too happy about.

The second hack of a washing machine was disclosed properly, although no firmware patch was ever released.

[1] https://news.ycombinator.com/item?id=29814973

[2] https://shakey.blot.im/reverse-engineering-a-popular-laundry...

> If you're using dockerized services (which are a must for NVidia-based CV, since their CV libraries are a dependency hell), you must use some kind of networking solution to communicate.

Eithen the two processes can share memory, in which case they don't need to communicate via network, much less RabbitMQ, or they can't, in which case the hack wouldn't have worked at all.

I was just curious if I could improve our PHP-based site’s performance. So I attached strace to an Apache process and followed the log of syscalls and counted milliseconds between them. Sure enough, I discovered that 20 ms was being spent each time on a DNS lookup to a statsd metrics collector service over UDP (I remember being told that this was lightweight, since it was UDP). PHP didn’t cache DNS lookups and this was sometimes happening many times per request. I added a static entry in /etc/hosts and the overall latency improved by 30% across all endpoints.

Another hack: I once was consulting for a client who was running Drupal and was going to launch their new site the next day, but suddenly it started crashing on some of the pages. I found out that you can take a core dump of Apache and load it into gdb. Then if you run some gdb macros, you can see the PHP stack trace at the time the crash occurred. Turns it it was some module (tokens?) they had recently enabled which was recursively calling into itself. Not sure why it didn’t hit some stack limit, though. We disabled the module, which fixed it and the client was super happy. If I knew more about Drupal, I probably would have disabled modules in a form of binary search as a first troubleshooting step. But I did know a little about gdb, so that came in handy.

WinNT 4 days, default permissions for windows/system32 were wide open. Replace default.scr with a copy of cmd.exe.log off and wait... Boom command prompt running as System. Easiest way without debug/admin permissions to get a copy of the windows PAM file. Think it may have still worked under Win2k. Eventually they stopped running Screensavers as the system account...

About 15 years ago, my brother used to run a shoutcast (Internet radio) server. He wasn’t getting many listeners since the list of stations people browse was sorted by popularity - number of listeners. So I disassembled and then hexedited the shoutcast server binary so that the initial number of listeners was 60-something (which meant the listener count would never drop below that). Then he actually started getting a few listeners :)