Glossary · Network

Port

Also callednetwork porttcp port

Definition

A port is a numeric label (0-65535) that identifies which application on a device a network connection is destined for.

Explanation

In depth

An IP address gets a packet to a device; a port gets it to the right application on that device. HTTP is conventionally on port 80, HTTPS on 443, SSH on 22, DNS on 53. Firewalls filter by port to block whole categories of traffic. Port 443 (HTTPS) is universally allowed because too much of the modern web depends on it — which is why circumvention traffic often gets tunnelled over 443 to blend in. Proxies expose specific ports for client connections (HTTP proxies typically 8080 or 3128, SOCKS often 1080). Web proxies use standard HTTPS 443 so they look like normal web traffic to intermediate networks.

Related terms

IP addressAn IP address is a numeric identifier assigned to each device on a network — how packets know where to go.TLS handshakeThe TLS handshake is the initial exchange between client and server that agrees on encryption keys and verifies the server's identity before any application data flows.HTTP proxyAn HTTP proxy is a proxy that understands HTTP and HTTPS traffic — it can read headers, cache responses, and rewrite requests.

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