This is a guide on how to configure an Ubuntu 20.04|18.04 & Ubuntu 16.04 LTS servers to authenticate against an LDAP directory server. LDAP is a lightweight client-server protocol for accessing directory services, specifically X.500-based directory services.
I expect you already have a running LDAP server, if not, use our guides below to set it up:
If you run the given command and see errors such as “Failed to connect”, there might be several reasons for this. One of the reasons might be issues encountered byesptool.py, the utility that is called by the build system to reset the chip, interact with the ROM bootloader, and flash firmware. One simple solution to try is manual reset described below, and if it does not help you can find more details about possible issues inTroubleshooting.
esptool.pyresets ESP32 automatically by asserting DTR and RTS control lines of the USB to serial converter chip, i.e., FTDI or CP210x (for more information, seeEstablish Serial Connection with ESP32). The DTR and RTS control lines are in turn connected toGPIO0andCHIP_PU(EN) pins of ESP32, thus changes in the voltage levels of DTR and RTS will boot ESP32 into Firmware Download mode. As an example, check theschematicfor the ESP32 DevKitC development board.
In general, you should have no problems with the official esp-idf development boards. However,esptool.pyis not able to reset your hardware automatically in the following cases:
Your hardware does not have the DTR and RTS lines connected toGPIO0andCHIP_PU
The DTR and RTS lines are configured differently
There are no such serial control lines at all
Depending on the kind of hardware you have, it may also be possible to manually put your ESP32 board into Firmware Download mode (reset).
For development boards produced by Espressif, this information can be found in the respective getting started guides or user guides. For example, to manually reset an esp-idf development board, hold down theBootbutton (GPIO0) and press theENbutton (CHIP_PU).
For other types of hardware, try pullingGPIO0down.