Remote Serial Ports

It is possible to connect to any networked remote serial port that supports RFC2217 (Telnet) protocol. To do this, specify the serial port to esptool as rfc2217://<host>:<port>. For example: --port rfc2217:// flash_id

Custom baud rates and DTR/RTS automatic resetting are supported over the RFC2217 protocol, the same as for a local serial port.

Pyserial Example Servers

PySerial (which is a dependency of esptool) includes two RFC2217 example programs - a single-port example and a multi-port example. These example servers can run on any OS that supports pyserial, and are the simplest way to connect to an Espressif SoC over the network.

There is an issue with automatic resetting due to network latency. In order to work around this issue, a modified version of the single-port server example called is provided with esptool.

On server: -p 4000 /dev/ttyUSB1

On client: --port rfc2217://ADDRESS_OF_SERVER:4000?ign_set_control flash_id

Raw Sockets

For servers or hardware network/serial adapters which don’t support the full RFC2217, it is also possible to specify --port socket://<host>:<port> syntax for a simple “raw TCP socket” protocol.

These raw sockets don’t support setting the baud rate or automatic resetting into the bootloader. If using this mode, don’t pass the --baud option to esptool. You need to set the baud rate manually on the server, and manually reset the chip into the bootloader mode (or use some other signalling/control method to tell the server to do so).

Here’s a very basic example using the common Linux/OSX command line “netcat” and “stty” commands:

On server:

stty -F /dev/ttyUSB1 230400  # set baud rate
nc -p 4000 -lk < /dev/ttyUSB1 > /dev/ttyUSB1

On client: -p socket://localhost:4000 flash_id


Using RFC2217 is strongly recommended where possible.

More Details

All of the remote serial port support comes via pyserial. Read more here. (Please keep in mind that the link points to documentation for the most recent pyserial version. You may have an older version.)