TCP UDP Ports Table

The registry is a formal process with a designated allocator; popular community software often skips it and wins by adoption instead. Minecraft's 25565, IRC's 6667 and RabbitMQ's management port 15672 are de facto standards - documented in vendor docs, expected by every tutorial, but formally unassigned. That gap is exactly why the table labels them: a compliance audit cares about the registry, a network engineer cares about reality.

They are separate namespaces: TCP 53 and UDP 53 are different channels, and both exist for DNS because zone transfers want TCP reliability while lookups want UDP speed. The protocol column shows which transports each service registered. Firewalls treat them independently too - allowing TCP 443 does nothing for QUIC, which rides UDP 443 and needs its own rule.

The well-known range inherited a Unix privilege convention: binding required root so users could not impersonate system services. Modern Linux ships with unprivileged_port_start tuned lower, and containers routinely bind 80 as a non-root process with capabilities - but the convention still shapes defaults, and confusing errors like permission denied on port 80 almost always trace back to it.

On the same transport, no: one TCP 443 listener per interface is the rule, which is why reverse proxies exist - nginx or a load balancer owns 443 and routes by hostname (SNI) to internal services on unexposed ports. The table shows sibling services on 8080/8443 for exactly this pattern: application servers hiding behind a proxy that speaks the public port.