Internet-Security.com TCP port 4433 details

OpenSSL’s test server (s_server) commonly listens on TCP 4433 in official examples and tutorials (for example: openssl s_server -accept 4433 -www) for ad‑hoc TLS testing.
LibreSSL and BoringSSL example servers similarly document or default to TCP 4433 for local TLS testing during development.
IANA registers 4433/tcp for the Versile Object Protocol (VOP), implemented by the Versile software stack.
Various TLS/HTTP testing setups in the open-source ecosystem (e.g., sample configs and interop demos) frequently pick TCP 4433 as an alternate HTTPS port when 443 is in use.

TCP 4433