A very common task during an IoT pentest is to find a device’s UART console. UART stands for Universal Asynchronous Receiver-Transmitter. On Linux-based IoT devices, UART is used to provide debugging access to the Linux system’s console shell. One requirement for interacting with a UART interface is its baud rate. The baud rate is a measure of the number of bits per second that are transmitted across the serial interface.
Common Baud Rates #
By far, the most common UART baud rate on IoT devices is 115200. This is always my first guess.
Below is a table of some of the most common baud rates that were extracted from minicom’s source code.
| Baud Rate (bits/second) |
|---|
| 9600 |
| 19200 |
| 38400 |
| 57600 |
| 115200 |
| 230400 |
A common method of finding the correct baud rate is guessing baud rates from the table above in decreasing order. Older devices will often have baud rates lower than 115200 due to hardware limitations.
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