Data Transfer Protocols Handbook

Network protocols are a set of rules and standards that enable devices to exchange data on a network. Each protocol performs a unique task, from basic data packet transfer to secure remote server management. Understanding these protocols is essential for configuring networks, developing applications, and ensuring cybersecurity. This reference presents the main protocols, grouped by their layer and purpose within the Open Systems Interconnection (OSI) model.

Internet Layer Protocols

These protocols are responsible for basic data transfer, addressing, and routing in networks.

IP (Internet Protocol)

IP is the fundamental protocol of the internet, responsible for addressing and routing data packets between devices on the network. Each device is assigned a unique IP address. IP does not guarantee packet delivery—that task is handled by higher-layer protocols, such as TCP.

ICMP (Internet Control Message Protocol)

ICMP is used by network devices (e.g., routers) to send error messages and operational information. For example, the ping utility uses ICMP to check the reachability of a host on the network, and traceroute uses ICMP to determine the path of packets.

Transport Protocols

These protocols enable the transfer of data between applications on different hosts.

TCP (Transmission Control Protocol)

TCP is a reliable, connection-oriented protocol. Before transmitting data, it establishes a connection (a "handshake"), guaranteeing the delivery of packets, their integrity, and the correct sequence. It is used in applications where reliability is important, such as web pages (HTTP), email (SMTP), and file transfers (FTP).

UDP (User Datagram Protocol)

UDP is a simpler, connectionless protocol. It sends data packets without guaranteeing their delivery or order. This makes it less reliable but significantly faster than TCP. It is ideal for streaming video, voice communications (VoIP), and online gaming, where speed is more important than 100% data integrity.

Application Protocols

These protocols run on top of transport protocols and provide functionality for specific user tasks.

HTTP (HyperText Transfer Protocol)

HTTP is the basis for data exchange on the World Wide Web. It is used to load web pages in a browser using a request-response scheme. The client (browser) sends an HTTP request to the server, which returns an HTTP response with the requested content (HTML, CSS, images).

HTTPS (HTTP Secure) - Secure HTTP

HTTPS is a secure version of HTTP that encrypts all data between the browser and the server using SSL/TLS protocols. It provides confidentiality (protection from eavesdropping), integrity (protection from modification), and authentication (assurance that you"re communicating with the right website).

FTP (File Transfer Protocol)

FTP is used to transfer files between a client and a server over a network. It uses separate connections for control (port 21) and data transfer. It is now often replaced by more secure protocols such as SFTP or SSH.

SSH (Secure Shell)

SSH provides a secure, encrypted channel for remotely managing servers and network devices. It allows you to execute commands, transfer files, and tunnel traffic of other protocols, protecting them from eavesdropping.

DNS (Domain Name System)

DNS is often called the "phone book of the internet." This protocol translates human-readable domain names (e.g., google.com) into machine-readable IP addresses (e.g., 142.251.132.46), which are used for packet routing.

SMTP (Simple Mail Transfer Protocol)

SMTP is the standard protocol for sending outgoing email. It is responsible for routing messages from an email client (e.g., Outlook) to the mail server and between mail servers.

POP3 (Post Office Protocol v3)

POP3 is a protocol for downloading email messages from the server to the client"s local device. Typically, after downloading, messages are deleted from the server, allowing email management to be concentrated on a single device.

IMAP (Internet Message Access Protocol)

IMAP, unlike POP3, allows email management directly on the server. All emails, folders, and their statuses are synced across all the client"s devices (phone, computer, tablet). This is the modern standard for working with email.

Security Protocols

These protocols do not transmit data themselves, but rather provide security for other protocols.

SSL/TLS (Secure Sockets Layer / Transport Layer Security)

SSL and its successor TLS are cryptographic protocols designed to provide secure communications over TCP. They provide encryption, server authentication, and data integrity. TLS is the basis for HTTPS, FTPS, SMTPS, and other secure protocols.

VPN (Virtual Private Network)

VPN is not a single protocol, but a technology that uses various protocols (such as OpenVPN, WireGuard, IPsec) to create an encrypted "tunnel" over a public network (the internet). This allows for secure connections to a corporate network from outside or for protecting all internet traffic.

Comparison Chart: TCP vs. UDP