Why TCP Needs Three Handshakes and Four Teardowns: A Beginner’s Guide

This guide explains TCP's three-way handshake and four-way termination, covering protocol characteristics, key terminology, step‑by‑step packet flows, reasons behind each phase, TIME_WAIT details, abnormal scenarios, and common interview questions for networking fundamentals.

Four‑Way TeardownTCPThree-way handshake

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Why TCP Needs Three Handshakes and Four Teardowns: A Beginner’s Guide

Architecture Digest

Oct 13, 2020 · Fundamentals

Understanding TCP Protocol: Header Fields, Three‑Way Handshake, and Four‑Way Teardown

This article explains the TCP protocol’s header structure, the purpose of each field, how the three‑way handshake establishes a reliable connection, why three steps are needed, and the four‑step process used to gracefully close a TCP session, including verification with Wireshark.

Four‑Way TeardownNetworking FundamentalsTCP

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Understanding TCP Protocol: Header Fields, Three‑Way Handshake, and Four‑Way Teardown

Programmer DD

Jan 21, 2019 · Fundamentals

Why Does TCP Need a Three‑Way Handshake and a Four‑Way Teardown? A Deep Dive

This article explains the principles behind TCP's three‑way handshake and four‑way teardown, covering connection establishment, data transfer, termination, header fields, state diagrams, sequence‑number wraparound, SYN‑flood attacks, mitigation techniques, and a practical Redis packet‑capture analysis, all illustrated with diagrams and code snippets.

Four‑Way TeardownLinuxSYN Flood

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Why Does TCP Need a Three‑Way Handshake and a Four‑Way Teardown? A Deep Dive