Basic Format: 
PROXY_USERNAME-session-YOUR_ID:PASSWORD
Complete Example with All Parameters: 
curl -x https://network.joinmassive.com:65535 \
-U '{USERNAME}-session-37-sessionttl-30-sessionmode-flex:{PASSWORD}' \
https://cloudflare.com/cdn-cgi/trace
Parameters Explained:
  • session-37: Unique session identifier
  • sessionttl-30: 30-minute session duration
  • sessionmode-flex: Flexible session mode
  • Port 65535: HTTPS (Use 65534 for HTTP, 65533 for SOCKS5)