Port 194

Internet Relay Chat (IRC) is a long-standing protocol standardized by the IETF as RFC 1459, allowing users to communicate via channels or private messages in real-time. IRC connections typically begin with a TCP handshake on port 194, after which the client identifies itself with a nickname and optionally authenticates with the server. Once connected, users can join or create channels (prefixed with a ‘#’) supporting multiple participants.

Underlying the simple client-server communication model is a network of interconnected servers forming large IRC networks. Servers synchronize channel data and participant presence, enabling global chat rooms spanning multiple servers. The protocol supports extensions like Direct Client-to-Client (DCC), enabling file transfers and private chat connections, which can bypass the server for peer-to-peer communication.

IRC is plaintext by design, lacking built-in encryption or authentication. It transmits all messages and credentials as unencrypted ASCII text. Clients can use either TCP or UDP, with TCP ensuring reliable delivery and UDP sometimes used for specific extensions, though most communication defaults to TCP. The protocol’s simplicity made it easy to implement in minimal clients, contributing to its early widespread adoption.