Enabling HTTP/2 protocol support in Nginx, on the CRYSTAL v1.0 project

1. Description of the HTTP/2 protocol.

HTTP/2 is a modern version of the HTTP protocol designed to address the limitations of HTTP/1.1 and improve the performance of web applications.

Key technical improvements:

• Multiplexing: multiple requests and responses are transmitted simultaneously over a single TCP connection, without blocking.
• Header Compression (HPACK): reduces data redundancy and speeds up the exchange of information between the client and server.
• Server Push: allows the server to pre-send resources such as styles, scripts, and images before the browser itself requests them. This reduces latency and speeds up page loading.
• Binary format: simplifies parsing HTTP messages on the server and client side, which reduces overhead and speeds up data transfer.
• Prioritization: critical resources (such as CSS or JavaScript) are transferred to the client with priority, speeding up page rendering.

In addition to improving performance, HTTP/2 improves site security by mandating the use of TLS in most browsers, modern cryptographic algorithms, and protecting against a number of attacks relevant to HTTP/1.1.

2. Enabling HTTP/2 protocol support.

To enable support for the HTTP/2 protocol, run the commands below in sequence:

nano /etc/nginx/sites-available/crystal

In the window that opens, find all lines of the following type:

listen 443 ssl;

and replace them with:

listen 443 ssl http2;

After replacing, press sequentially - 'ctrl + x', 'y', 'Enter'.

Next, enter the command:

systemctl restart nginx && curl -I --http2 https://YourDomain

The first line of the output should contain - 'HTTP/2 200', this means that the protocol connection - HTTP/2, successful.

You can make the site much more secure by adding some rules to the Nginx server, according to this instructions.