2024-08-31: Debug Log: Internet doesn't work (it was the PSU)

A photo of an open-bench mounted server in a server rack.

I woke up in the morning, got to the desk in my home office, checked my email, discord, and the news. Then I switched from my desktop to my laptop and... there's no internet.

That's weird. I just browsed the net on my PC, so what's up with the laptop? Both are connected to the same network, so it's not the problem of the network not having connectivity. As such, the problem lies between my ISP's modem and the laptop (inclusive).

I started with disconnecting and reconnecting the ethernet network cable (it's a pretty stationary laptop, so I keep it wired). That didn't fix anything, apart from displaying a short spinning animation indicating it's trying to get an IP address assigned (a DHCP issue then?). Just to be sure it's nothing on the laptop side I did a reboot, and then power-cycled the nearest network switch for good measure as well. No luck.

Following up on the DHCP lead I logged into my home server, which runs the DHCP daemon... wait... what is this?

ssh: connect to host home server port 22: No route to host

So I moved the chair a bit to check my server rack, and found the home server dark. That's unusual. On closer inspection actually the LEDs on the motherboard next to the power/reboot buttons were lit. A minor explanation here: I use customized Open Benchtable mounts, so the mobo is easily accessible; at the same time it means there are no power/reboot buttons on the case – as there is no case – so I rely on mobos having power/reboot buttons directly on them (or, failing that, small buttons-on-PCBs that you hook into the normal case button connector on the mobo).

I clicked the power button, and... even the two last LEDs went dark. Not great. They did light back up a few seconds later though, so re-tried a couple of times, with the same result. The closest I got to a "fully functional and running server" was the CPU fan spinning up for 0.5 seconds.

At this point I had good news and bad news:

  • Good news: I found the problem! DHCP server is down because...
  • Bad news: ...the server is dead.

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2024-11-05: Jak rozkodować nieznany protokół sieciowy i ściągnąć SECRET.PDF

W przyszłym tygodniu zaczyna się pierwsze szkolenie z mojej serii "Pliki i Protokoły Binarne" (rejestracja jest nadal otwarta – serdecznie zapraszam). Poniższy filmik pokazuje w praktyce to, czego można nauczyć się podczas tej serii – tj. zaczynamy od przechwyconego ruchu sieciowego (PCAP/Wireshark), rozgryzamy użyty protokół binarny, a potem go na szybko implementujemy (Python) i ściągamy brakujący plik SECRET.PDF. Miłego oglądania!

Czytaj dalej... [ 0 komentarzy ]

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