TCP/IP

TCP/IP is the foundational protocol suite of the internet, named after its two core protocols: the Transmission Control Protocol (TCP) and the Internet Protocol (IP). It is organized into layers, where IP handles addressing and routing packets between machines, and TCP layers reliability on top of it, guaranteeing that bytes arrive in order and retransmitting anything lost. Almost every service a sovereign Bitcoiner self-hosts, from a node's peer connections to a web dashboard, rides on this stack.

Layers and responsibilities

The model splits work into roughly four layers: the link layer (Ethernet, Wi-Fi), the internet layer (IP, which assigns addresses and forwards packets hop by hop), the transport layer (TCP for reliable streams, or UDP for lightweight datagrams), and the application layer (HTTP, DNS, SSH, and the Bitcoin and Lightning protocols). Each layer wraps the data from the layer above with its own header, a process called encapsulation.

Why it matters for self-hosting

Understanding which port and protocol a service uses is the difference between a node that accepts inbound connections and one that is silently unreachable. Bitcoin Core listens on TCP port 8333; Lightning daemons, block explorers, and your router's forwarding rules all reason in terms of IP addresses and TCP or UDP ports. Knowing the stack lets you diagnose why a peer cannot connect or why a port-forward never took effect.

TCP/IP is the substrate beneath every other networking concept in this glossary. To learn how names map to the addresses it routes, see DNS; to understand why home services are often unreachable from outside, see Network Address Translation (NAT).