IP addresses, ports and the shape of a connection

An IP address identifies an interface on a network so packets can reach it. Private addresses work inside a local network, while public addresses are reachable through the internet. Routers translate between them with NAT in many home networks.

How it works

A port identifies a service on a device, such as a web server or an SSH service. An open port is not automatically a vulnerability, but every exposed service increases the surface that must be updated and configured correctly.

Practical takeaways

Keep administrative services behind a firewall or VPN, use keys and multi-factor authentication where possible, and expose only the ports a service actually needs. When troubleshooting, separate a DNS problem from a routing problem and a service problem.

An IP address tells you where; a port helps identify which service should receive the traffic.

In short: Networking becomes easier to reason about when you distinguish names, addresses, routes and services.