QUIC
also: Quick UDP Internet Connections, HTTP/3, IETF QUIC
QUIC is a modern transport protocol that runs over UDP instead of TCP, designed to improve connection speed, reliability, and security for web traffic and other applications.
QUIC (Quick UDP Internet Connections) is a transport-layer protocol developed by Google that replaces TCP for many use cases. It combines the speed of UDP with TCP-like reliability features, built directly into the protocol rather than relying on separate encryption layers.
Key advantages include faster connection establishment (0-RTT resumption), improved performance over high-latency or lossy networks, and integrated encryption (TLS 1.3). QUIC multiplexes multiple streams over a single connection, allowing independent stream loss without blocking others—unlike TCP where a single lost packet blocks all data.
On Linux, QUIC is increasingly used by web browsers and servers (HTTP/3), DNS over QUIC (DoQ), and VPN applications. You may see QUIC traffic using port 443 over UDP. Tools like tcpdump and wireshark can capture and analyze QUIC packets, though the encrypted nature means you won't see payload details without decryption keys.