Blynk server has 3 ports open for different security levels.

• 8441 - SSL/TLS connection for hardware
• 8442 - plain TCP connection for hardware (no security)
• 8443 - mutual authentication (mutual SSL) connection for Mobile Apps

Hardware may select to connect to 8441 or 8442, depending on it's capabilities.

Most platforms are not capable to handle SSL, so they connect to 8442. However, our gateway script can be used to add SSL security layer to communication.

./blynk-ser.sh -f SSL

This will forward all hardware connections from 8441 port to the server via SSL gateway. You can run this script on your Raspberry Pi, desktop computer, or even directly on your router!

Note: when using your own server, you should overwrite the bundled server.crt certificate, or specify it to the script using --cert switch:

./blynk-ser.sh -f SSL -s <server ip> -p 8441 --cert=<certificate>.crt

Flag "-f SSL" is enabled by default for USB communication so you don't have to explicit declare it. Note: SSL is supported by the gateway only on Linux/OSX for now

If you want to skip SSL, and connect to TCP, you can also do that:

./blynk-ser.sh -t TCP

In order to gain maximum security you could install Blynk server locally and restrict access to your network, so nobody except you could access it. See how to install Blynk server locally here.