SIOT Logs

Blinking only drives an output on a timer. Button-to-LED also has to read an input, so the program has to react to the outside world: configure a pin as input, give it a defined idle level, and decide when to check it. The blink program only ever writes: set the pin high, wait, s...

Quiz: SIOT / GPIO Input and I2C Sensor Wiring on the ESP32 | updated: Oct 20, 2026

GET is defined as safe: clients, browsers, proxies and crawlers may send it at any time, repeat it, prefetch it or cache it, assuming nothing happens. A door that opens on GET can be opened by a link preview, a prefetch or a retry, and the command is trivial to trigger and repeat...

Quiz: SIOT / Sniffing and Replaying IoT Traffic | updated: Oct 20, 2026

idf.py monitor expects an ESP-IDF project and uses its ELF file to decode crash addresses. With only a .bin there is no project and no ELF. Any plain serial terminal works instead, as long as it uses the firmware's baud rate, 115200 by default. idf.py monitor is a serial terminal...

Quiz: SIOT / Sniffing and Replaying IoT Traffic | updated: Oct 20, 2026

Enable the internal pull-up on IO4. Released, the resistor pulls the pin up to 3.3 V and it reads 1. Pressed, the button connects the pin to GND and it reads 0. The button is active low. * The pull-up gives the pin a level when the switch is open; the switch only ever pulls it d...

Quiz: SIOT / GPIO Input and I2C Sensor Wiring on the ESP32 | updated: Oct 20, 2026

A free, open-source packet analyser. It captures every packet entering or leaving a network interface (through the pcap library) and decodes each one layer by layer: addresses, ports, protocol fields and, for unencrypted traffic, the payload itself. Wireshark runs on Linux, macOS...

Quiz: SIOT / Sniffing and Replaying IoT Traffic | updated: Oct 20, 2026

Read the whole flash (firmware, Wi-Fi credentials, server addresses, keys) and write their own firmware. Flash encryption makes the dump unreadable, and secure boot makes the chip refuse unsigned firmware. The same tool that flashes a board also reads it. esptool read-flash 0 0x4...

Quiz: SIOT / Sniffing and Replaying IoT Traffic | updated: Oct 20, 2026

While the button is open, the pin is floating: connected to nothing, so it picks up noise and reads random 0s and 1s. The LED flickers, or turns on when you only touch the wire. A digital input draws almost no current. That is what makes it good at sensing a voltage, and also wha...

Quiz: SIOT / GPIO Input and I2C Sensor Wiring on the ESP32 | updated: Oct 20, 2026

tcpdump is the lightweight command-line capturer: it records raw packets from the interface (-i wlp4s0, the Wi-Fi card) into a pcap file (-w capture.pcap). Wireshark is the graphical analyser that opens that file to filter and decode it. Both need root because capturing reads raw...

Quiz: SIOT / Sniffing and Replaying IoT Traffic | updated: Oct 20, 2026

GPIO0 is a strapping pin. If it is low at reset, the ESP32 enters its serial bootloader (download mode) instead of running the app. A button from GPIO0 to GND held during reset does exactly that, which is also how the board's own BOOT button works. At reset the ESP32 samples a fe...

Quiz: SIOT / Sniffing and Replaying IoT Traffic | updated: Oct 20, 2026

The metal contacts bounce: for a few milliseconds the switch opens and closes rapidly before it settles, so the pin sees several edges. Debouncing accepts a new state only after it has been stable for a while, typically 10-50 ms. * The chip is fast enough to see every bounce as...

Quiz: SIOT / GPIO Input and I2C Sensor Wiring on the ESP32 | updated: Oct 20, 2026