SIOT Logs

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

In normal (managed) mode, only traffic to or from the laptop itself, plus broadcast and multicast. To see frames between other stations it has to switch the card into monitor mode. On an open network those frames are then readable; with WPA2/3 they are encrypted. A Wi-Fi card in...

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

Polling: a task reads the pin every few milliseconds and sleeps in between. Interrupt: the pin's edge triggers an ISR that wakes a waiting task. Polling is simpler and filters bounce. An interrupt reacts at once and uses no CPU while idle. * Both end in a task setting the LED; t...

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

The traffic is unencrypted and unauthenticated. By sniffing one real "open" request, the attacker learns the server's address, port and the exact request, and can send the same request again: a replay attack. * The server cannot tell the replayed request from the real one. * The...

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