esp-idf/examples/protocols/sockets/tcp_client/README.md

| Supported Targets | ESP32 | ESP32-C2 | ESP32-C3 | ESP32-S2 | ESP32-S3 | Linux |
| ----------------- | ----- | -------- | -------- | -------- | -------- | ----- |


# TCP Client example

(See the README.md file in the upper level 'examples' directory for more information about examples.)

The application creates a TCP socket and tries to connect to the server with predefined IP address and port number. When a connection is successfully established, the application sends message and waits for the answer. After the server's reply, application prints received reply as ASCII text, waits for 2 seconds and sends another message.

## Configure the project
This example can be configured to run on ESP32 and Linux target to communicate over IPv4 and IPv6.

```
idf.py menuconfig
```

Set following parameters under ```Example Configuration``` Options:

* Set `IP version` of example to be IPV4 or IPV6.

* Set `IPV4 Address` in case your chose IP version IPV4 above.

* Set `IPV6 Address` in case your chose IP version IPV6 above.
    * For IPv6 there's an additional option for ```Interface selection```.
    * Enter the name of the interface to explicitely establish communication over a specific interface.
    * On selecting ```Auto``` the example will find the first interface with an IPv6 address and use it.

* Set `Port` number that represents remote port the example will connect to.

Configure Wi-Fi or Ethernet under "Example Connection Configuration" menu. See "Establishing Wi-Fi or Ethernet Connection" section in [examples/protocols/README.md](../../README.md) for more details.


Note: please replace `192.168.0.167 3333` with desired IPV4/IPV6 address (displayed in monitor console) and port number in the following command.


## How to use example:

In order to create TCP server that communicates with TCP Client example, choose one of the following options.

There are many host-side tools which can be used to interact with the UDP/TCP server/client.
One command line tool is [netcat](http://netcat.sourceforge.net) which can send and receive many kinds of packets.

In addition to those tools, simple Python scripts can be found under sockets/scripts directory. Every script is designed to interact with one of the examples.

### TCP server using netcat
```
nc -l 192.168.0.167 3333
```

### Python scripts
Script example_test.py could be used as a counter part to the tcp-client project, ip protocol name (IPv4 or IPv6) shall be stated as argument. 

Note that this script is used in automated tests, as well, so the IDF test framework packages need to be imported.
Please run the following commands to configure the terminal to execute the script.
```
export PYTHONPATH="$IDF_PATH/tools:$IDF_PATH/tools/ci/python_packages"
python -m pip install -r $IDF_PATH/tools/ci/python_packages/ttfw_idf/requirements.txt
```

Example:
```
python example_test.py IPv4
```
## Hardware Required

This example can be run on any commonly available ESP32 development board.
This example can also run on any Linux environment.


## Build and Flash

Build the project and flash it to the board, then run monitor tool to view serial output:

```
idf.py -p PORT flash monitor
```

(To exit the serial monitor, type ``Ctrl-]``.)

See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.


## Troubleshooting

Start server first, to receive data sent from the client (application).