Sockets

Ports and Sockets

Understand port number ranges and how a socket, the pairing of an IP address and port, identifies a network endpoint.

What is Inter-Process Communication (IPC)?

Inter-process communication (IPC) is the set of mechanisms an operating system provides for separate processes — each with its own isolated address space — to…

What are Sockets as an IPC Mechanism?

A socket is a bidirectional communication endpoint, addressed by the kernel’s networking or Unix-domain stack, that lets two processes exchange data using the…

What is a Socket?

A socket is an endpoint for network communication, uniquely identified by the combination of an IP address, a port number, and a transport protocol (TCP or UDP…

What is a Port in Networking?

A port is a 16-bit number (0–65535) that identifies a specific process or service on a device, letting a single IP address handle many simultaneous network con…

What is netstat?

netstat is a command-line utility that displays active network connections, listening ports, routing tables, and per-protocol statistics on a host, making it a…

What is the TCP State Machine?

The TCP state machine is the finite set of connection states, such as CLOSED, LISTEN, SYN_SENT, SYN_RECEIVED, ESTABLISHED, FIN_WAIT_1/2, CLOSE_WAIT, LAST_ACK,…

How Does TCP Connection Teardown Work?

TCP connection teardown normally uses a four-step FIN/ACK exchange: the side closing first sends a FIN, the peer acknowledges it and later sends its own FIN on…