TCP/IP Protocol

The Transmission Control Protocol/Internet Protocol (TCP/IP) is a suite of communication protocols used to interconnect network devices on the internet and other computer networks. It is the de facto standard for internet communications.

Overview

TCP/IP is designed as a layered protocol suite, with each layer providing services to the layer above it and utilizing the services of the layer below it. This modularity allows for flexibility and extensibility. The primary layers of the TCP/IP model, as commonly described, are:

Application Layer: Protocols like HTTP, FTP, SMTP, DNS.
Transport Layer: Protocols like TCP (reliable, connection-oriented) and UDP (unreliable, connectionless).
Internet Layer: Protocols like IP (Internet Protocol) for addressing and routing packets.
Network Access Layer (or Link Layer): Protocols for physical network transmission (e.g., Ethernet, Wi-Fi).

Key Components and Concepts

Transmission Control Protocol (TCP)

TCP provides reliable, ordered, and error-checked delivery of a stream of bytes between applications running on hosts communicating over an IP network. Key features include:

Connection-Oriented: Establishes a connection before data transfer (three-way handshake).
Reliability: Uses acknowledgments and retransmissions to ensure data arrives correctly.
Flow Control: Manages the rate of data transmission to prevent overwhelming the receiver.
Congestion Control: Manages network traffic to avoid network congestion.

Internet Protocol (IP)

IP is responsible for addressing hosts and routing packets of data from a source host to a destination host. Key aspects include:

Addressing: Assigns unique IP addresses (IPv4 and IPv6) to devices.
Routing: Determines the best path for packets to travel across networks.
Datagrams: Data is sent in independent packets called datagrams.

Sockets API

The Windows Sockets API (Winsock) provides an interface for network programming, allowing applications to interact with TCP/IP and other network protocols.

Common socket operations include:

socket(): Creates a socket.
bind(): Assigns a local address and port to a socket.
listen(): Puts a socket into a listening mode for incoming connections (for TCP servers).
accept(): Accepts an incoming connection (for TCP servers).
connect(): Establishes a connection to a remote host (for TCP clients).
send() / recv() or sendto() / recvfrom(): Sends and receives data.
closesocket(): Closes a socket.

Related APIs and Structures

SOCKADDR_IN: Structure used to specify an internet protocol address.
WSAStartup() / WSACleanup(): Functions to initialize and terminate the Winsock DLL.
Address Family (AF_INET, AF_INET6): Specifies the protocol family.
Socket Type (SOCK_STREAM, SOCK_DGRAM): Specifies the communication semantics.