Port 443 supports HTTPS and HTTP/3 and https (SCTP reference coverage) across distinct transports. Review each protocol before writing firewall or monitoring policy.
Secure HTTP traffic protected by TLS.
Web applications, APIs, reverse proxies, load balancers and encrypted browser traffic.
Client to server
TLS version, cipher policy, certificate validity and application authorization remain separate security controls.
HTTP/3 carried over the QUIC transport protocol.
Modern browsers, CDNs, reverse proxies and APIs that negotiate HTTP/3.
Client to server
UDP 443 needs an explicit firewall path; services should retain a TCP HTTPS fallback and monitor QUIC separately.
https (SCTP reference coverage) is documented as a network service convention for port 443 over SCTP.
Use this reference entry when identifying or validating systems documented to use 443/SCTP.
Varies
Confirm the listening process and current vendor documentation before permitting traffic; a listed convention does not prove the active service or its security posture.