What is a Procotol? Common Network Protocols and Their Applications - Blog -

18/02/2025

What is a Procotol? Common Network Protocols and Their Applications

In our hyper-connected world, network protocols enable seamless communication between devices. They ensure data is transmitted efficiently and accurately, forming the backbone of the Internet and various digital applications. Understanding these protocols is essential for anyone involved in IT, telecommunications, or digital services. This article delves into the fundamental aspects of network protocols and explores some of the most common ones used today.

network procotols

What is a Network Protocol?

Network protocols are established rules and conventions that dictate how data is exchanged over networks. They define the syntax, semantics, and synchronization of communication, ensuring that devices from different manufacturers can communicate effectively. Protocols are crucial for maintaining order and standardization in digital communications, enabling interoperability among diverse systems.

Network protocols work at various layers of the OSI (Open Systems Interconnection) model, a conceptual framework used to understand network interactions in seven layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application. Each layer serves a specific function and communicates with the layers directly above and below it. Protocols operate at one or more of these layers, facilitating specific aspects of data transmission.

Why Do We Need a Network Protocol?

The complexity and diversity of modern communication systems require network protocols. Protocols provide a common language for devices, enabling them to exchange data reliably. They also ensure consistent communication, allowing devices to interpret and respond to data accurately. They facilitate error detection and correction, maintaining data integrity and preventing communication breakdowns. Without network protocols, the seamless operation of the Internet and other digital networks would be impossible.

For example:

Tom speaks Chinese, Jack speaks German, and they don’t understand each other’s language. In this case, no one knows what the other is saying. If at this time, a person named Mary comes who can speak both Chinese and German, he can serve as a “bridge” between Tom and Jack, translating Tom’s words into German for Jack, and translating Jack’s words into Chinese for Tom.

In the above example, “Mary” is the “network protocol”, providing a bridge for different data ends so that different data ends can communicate normally.

Moreover, network protocols enable scalability and flexibility in network design. They allow networks to expand and integrate new devices without significant changes to the existing infrastructure. This adaptability is crucial for supporting the rapid growth of internet-connected devices, also known as the Internet of Things (IoT).

What Are the Common Network Protocols?

Internet Protocol (IP)

The Internet Protocol is fundamental to the Internet, responsible for addressing and routing packets of data across networks. It works closely with TCP and UDP to ensure data reaches its intended destination.

There are two versions of IP:

IPv4: IPv4 is the most widely used version of the IP protocol. It uses 32-bit binary numbers to represent IP addresses and can theoretically provide about 4.3 billion IP addresses. However, with the rapid development of the Internet, IPv4 addresses have been gradually exhausted.

IPv6: IPv6 is the next-generation version of IPv4. It uses 128-bit binary numbers to represent IP addresses and can theoretically provide almost unlimited IP addresses. IPv6 solves the problem of IPv4 address exhaustion and also improves and enhances security and mobility.

Transmission Control Protocol (TCP)

TCP is a connection-oriented protocol that ensures reliable packet delivery. It establishes a connection before transmitting data, making it suitable for applications requiring accuracy, such as web browsing and email.

Before data transmission, a three-way handshake is required between the TCP client and the server to establish a connection. First, the client sends a SYN (synchronous sequence number) packet to the server to request a connection. After receiving the SYN packet, the server sends a SYN + ACK (acknowledgment number) packet to the client to indicate that it agrees to establish a connection. After receiving the SYN + ACK packet from the server, the client sends an ACK packet to the server to confirm that the connection has been established. Through the three-way handshake, a reliable connection is established between the client and the server.

User Datagram Protocol (UDP)

Unlike TCP, UDP is connectionless and focuses on speed rather than reliability. It is used in applications where fast data transmission is critical, such as online gaming and streaming services. UDP sends packets called datagrams without establishing a connection, reducing latency but sacrificing reliability and order.

Hypertext Transfer Protocol (HTTP/HTTPS)

HTTP is the foundation of data communication on the web, facilitating communication between web browsers and servers. HTTPS adds a layer of security, encrypting data to protect user privacy during transmission. HTTPS uses SSL/TLS protocols to encrypt data, ensuring secure transactions, especially on e-commerce sites.

TLS handshake process

1. ClientHello → 2. ServerHello → 3. Certificate verification → 4. Key exchange → 5. Encrypted communication

File Transfer Protocol (FTP)

FTP is used to transfer files between a client and a server. It is commonly employed in website management and data sharing, allowing users to upload and download files efficiently. Depending on the network configuration, FTP can operate in active or passive mode, to overcome firewall and NAT restrictions.

Simple Mail Transfer Protocol (SMTP)

SMTP is responsible for sending emails across networks. It works with protocols like IMAP and POP, which handle email retrieval, ensuring seamless email communication. SMTP operates over TCP and uses commands and responses to send and relay messages between mail servers.

Workflow

1. Client → SMTP server (port 25)

2. MX record query between servers

3. Incoming server (POP3/IMAP)

Domain Name System (DNS)

DNS translates human-readable domain names into IP addresses, enabling users to access websites without remembering complex numerical addresses. It is essential for web browsing and internet navigation. DNS operates in a hierarchical structure with root, top-level domain, and authoritative name servers, facilitating efficient domain resolution.

Dynamic Host Configuration Protocol (DHCP)

DHCP automates the allocation of IP addresses to devices on a network, simplifying network management and configuration. It ensures devices can connect to a network efficiently without manual IP address assignment. DHCP assigns IP addresses dynamically, ensuring optimal utilization of IP address space.

Internet Control Message Protocol (ICMP)

ICMP is used for error handling and diagnostics in network devices. It is commonly employed in tools like ping and traceroute, helping network administrators diagnose and troubleshoot network issues. ICMP sends error messages and operational information, such as destination unreachable or time exceeded, to indicate network connectivity issues.

Secure Shell (SSH)

SSH provides a secure channel over an insecure network, allowing command execution and file transfers. It is widely used for remote administration of network devices and servers, ensuring secure access and control. SSH uses encryption to secure data and authentication to verify users, providing a secure alternative to older protocols like Telnet.

Technical highlights

1. Asymmetric encryption (RSA/ECDSA) + symmetric encryption (AES/ChaCha20) double insurance

2. Anti-man-in-the-middle attack: verify host fingerprint when connecting for the first time

3. Port forwarding: easily break through firewall restrictions (ssh -L/-D/-R)

SSH Procotol

Application of Network Protocols

Network protocols are integral to various real-world applications. In the IT industry, they enable the development and maintenance of robust network infrastructures. Telecommunications rely on these protocols to provide reliable voice and data services. Online services, such as streaming platforms and e-commerce websites, depend on protocols to deliver content efficiently and securely. In every industry, network protocols ensure the smooth operation of digital services, enhancing productivity and user experience.

For instance, in video conferencing, protocols like TCP, UDP, and RTP (Real-time Transport Protocol) ensure high-quality audio and video transmission with minimal latency. In cybersecurity, protocols like HTTPS and SSH play a critical role in protecting sensitive information from unauthorized access and cyber threats.

With the rise of emerging technologies like 5G and IoT, the role of network protocols will become even more significant in ensuring efficient and secure data exchange. Future developments may focus on enhancing protocol performance, reducing latency, and improving security measures to address the challenges of tomorrow's digital landscape.