# Secure Sockets echo client demo
<a name="secure-sockets-demo"></a>

**Important**  <a name="archive-message"></a>
This is an archived version of the FreeRTOS User Guide for use with FreeRTOS release 202012.00. For the latest version of this document, see the [FreeRTOS User Guide](../../../latest/userguide/index.html).

The following example uses a single RTOS task. The source code for this example can be found at `demos/tcp/aws_tcp_echo_client_single_task.c`.

Before you begin, verify that you have downloaded FreeRTOS to your microcontroller and built and run the FreeRTOS demo projects. You can clone or download FreeRTOS from [GitHub](https://github.com/aws/amazon-freertos). See the [README.md](https://github.com/aws/amazon-freertos/blob/master/README.md) file for instructions. 

**To run the demo**

**Note**  
To set up and run the FreeRTOS demos, follow the steps in [Getting Started with FreeRTOS](freertos-getting-started.md).  
The TCP server and client demos are currently not supported on the Cypress CYW943907AEVAL1F and CYW954907AEVAL1F Development Kits.

1. Follow the instructions in [Setting Up the TLS Echo Server](https://docs.amazonaws.cn/freertos/latest/portingguide/tls-echo-server.html) in the FreeRTOS Porting Guide.

   A TLS echo server should be running and listening on the port 9000.

   During the setup, you should have generated four files:
   + `client.pem` (client certificate)
   + `client.key` (client private key)
   + `server.pem` (server certificate)
   + `server.key` (server private key)

1. Use the tool `tools/certificate_configuration/CertificateConfigurator.html` to copy the client certificate (`client.pem`) and client private key (`client.key`) to `aws_clientcredential_keys.h`.

1. Open the `FreeRTOSConfig.h` file.

1. Set the `configECHO_SERVER_ADDR0`, `configECHO_SERVER_ADDR1`, `configECHO_SERVER_ADDR2`, and `configECHO_SERVER_ADDR3` variables to the four integers that make up the IP address where the TLS Echo Server is running.

1. Set the `configTCP_ECHO_CLIENT_PORT` variable to `9000`, the port where the TLS Echo Server is listening.

1. Set the `configTCP_ECHO_TASKS_SINGLE_TASK_TLS_ENABLED` variable to `1`.

1. Use the tool `tools/certificate_configuration/PEMfileToCString.html` to copy the server certificate (`server.pem`) to `cTlsECHO_SERVER_CERTIFICATE_PEM` in the file `aws_tcp_echo_client_single_task.c`.

1.  Open `{{freertos}}/vendors/{{vendor}}/boards/{{board}}/aws_demos/config_files/aws_demo_config.h`, comment out `#define CONFIG_MQTT_DEMO_ENABLED`, and define `CONFIG_TCP_ECHO_CLIENT_DEMO_ENABLED`.

The microcontroller and the TLS Echo Server should be on the same network. When the demo starts (`main.c`), you should see a log message that reads `Received correct string from echo server`.