What are network protocols?

Network protocols are sets of rules that define how different devices on the network communicate and exchange information. Thanks to network protocols, you can communicate with anyone from around the world if their device is connected to the same network as yours.

But what is a network protocol in simple terms? It’s like a common language for computers. The protocol makes it possible for computers and other connected devices with different software, hardware, or internal processes to communicate with each other easily and safely.

Different types of network protocols play different roles in the exchange of information over the internet, intranets, and private networks. Network protocols can be broadly classified into three types: network communication protocols, network security protocols, and network management protocols.

Communication protocols set the rules and formats for transmitting data across a network. They define the syntax, semantics, authentication, synchronization, and error detection in analog and digital communications. Here are the essential network communication protocols:

• Hypertext Transfer Protocol (HTTP). The HTTP is an application layer protocol and is key for sharing data over the web. It allows communication between a server and a browser, and it transfers web pages on the internet.
• Network File System (NFS). The Network File System protocol allows users of a single network (clients) to remotely access files stored on a central machine (server). Newer versions of the protocol use TCP and UDP protocols for communication.
• Transmission Control Protocol (TCP). The TCP is a connection-oriented protocol that ensures reliable and error-free data packet transmission. The Transmission Control Protocol makes sure the data reaches the destination on time and in the order it was sent.
• User Datagram Protocol (UDP). The UDP is a fast and efficient connectionless protocol used for time-sensitive transmissions, such as video playback or online gaming. It does not establish a connection before sending data, nor does it guarantee delivery. The User Datagram Protocol is used in situations where speed is more critical than reliability. If you’re wondering which protocol is better, check out our article on TCP vs. UDP.
• File Transfer Protocol (FTP). The FTP transfers computer files in binary and text formats between a client and a server on a computer network.
• Internet Protocol (IP). The IP handles the addressing and routing of data packets across networks. IP addresses serve as unique identifiers for each device or host on the IP network, such as the internet. The internet protocol uses these addresses to determine the source and destination of data packets. You can visit our website to find out your IP address.
• Internet Control Message Protocol (ICMP). The ICMP is a network communication protocol for error reporting and diagnostics. It communicates information about network connectivity issues and is used for sending control messages.
• Address Resolution Protocol (ARP). Developers use the ARP for mapping IP addresses to corresponding hardware Media Access Control (MAC) addresses.

Network security protocols manage safe data transmission over a network and protect data from unauthorized access by using encryption and cryptography. The main network security protocols are:

• Transport Layer Security (TLS). The TLS is a network security protocol that ensures data integrity, security, and privacy. It encrypts data transmitted between two communicating applications, such as a web server and browser. The TLS is more secure and efficient than its predecessor, SSL.
• Hypertext Transfer Protocol Secure (HTTPS). The HTTPS is an extension of the HTTP protocol. It uses either TLS or SSL to encrypt the data that a browser and a website exchange. The HTTPS protects data during transfer from eavesdropping, tampering, and man-in-the-middle attacks.
• Secure Socket Layer (SSL). The SSL is a cryptographic protocol used for the protection of sensitive data and internet connections with encryption. The SSL enables server-client communication and server-server communication.
• Secure File Transfer Protocol (SFTP). The SFTP is a network protocol that provides file access, transfer, and management functionalities over a secure data stream. The SFTP is typically used for transferring files between systems and for encrypting commands and data.

Network management protocols help network administrators diagnose problems and perform troubleshooting tasks, ensuring smooth communication across a computer network. These protocols describe procedures and policies for managing, monitoring, and maintaining the performance of a network. The following are the most popular network management protocols:

• Simple Network Management Protocol (SNMP). The SNMP helps network administrators to manage network devices, track network performance, and pinpoint glitches to quickly solve network problems. The SNMP exchanges management information between network devices and the central manager.
• Internet Control Message Protocol (ICMP). Network devices use the IICMP to report errors and implement diagnostic functions in IP networks. The ICMP is crucial for network debugging and messaging, for example, sending the “ping” command to test connectivity.
• Network Time Protocol (NTP). The NTP’s purpose is to synchronize the time between computer systems and network devices to ensure accurate and consistent timekeeping across a network.
• Dynamic Host Configuration Protocol (DHCP). The DHCP dynamically allocates IP addresses to devices when they connect to the network. It also provides devices with subnet masks, default gateways, and DNS server addresses.

Network protocols work by breaking down large processes into smaller tasks and functions to help connected devices communicate across a network. Network protocols cooperate at every level of the network in order to facilitate efficient and secure information exchange.

This breakdown and cooperation are typically structured according to a layered model, such as the Open Systems Interconnection (OSI) model, where each layer specifies aspects of the network communication process.

The Open Systems Interconnection (OSI) model layers are part of this abstract representation of how different protocols interact and work together across various layers of network communication. It illustrates how communication layers are built upon each other, facilitating communication between network devices.

The OSI model divides the networking process into seven distinct layers with specific functions and responsibilities. This approach of network layering helps to standardize the network functions to allow interoperability of different network technologies and devices.

It’s important to know how different protocols operate on each of the seven OSI model layers to have a clearer picture of how network communication works. Here are the seven OSI model layers:

1. Physical layer. The physical layer establishes and maintains the physical connection between two network devices. It transmits data in raw bits over the physical medium, such as cables, and utilizes electrical or light signals. In this layer, network protocols convert digital data into a form that can be physically transmitted over network communication mediums.
2. Data link layer. The data link layer is responsible for framing, which means breaking down data packets into frames for transmission. It ensures the reliable transmission of these frames between physically connected nodes, and manages the creation, maintenance, and termination of these link-level connections.
3. Network layer. The network determines the most optimal physical path for data packets to take from one network device to another, handling routing and forwarding in the network. It splits up data from applications into packets and puts the packets back together into the original data stream at the receiver’s end.
4. Transport layer. The transport layer manages end-to-end data transmission in a network, ensuring the reliability and integrity of data by applying error-checking and correction mechanisms. It is responsible for data flow control, which includes determining how much data to send, where to send it, and the timing of its delivery. The transport protocol transmits data using the TCP and UDP.
5. Session layer. The session layer establishes, manages, and terminates sessions (the communication channels) between applications on network devices that want to exchange data. This layer utilizes established ports to manage and maintain individual sessions, so that multiple applications could communicate simultaneously.
6. Presentation layer. The presentation layer is responsible for translating and formatting data between the network and the application layer, ensuring that data is in correct syntax and semantic format for the application. It handles encryption and decryption of data for secure transmission. This layer also handles data compression to optimize data transfer.
7. Application layer. The application layer provides network services directly to end-user applications. It enables users, both human and software, to perform network-related tasks such as reading messages, transferring files, and using internet-connected applications like web browsers, email clients, and communication tools. This layer presents data in a user-friendly and accessible format and bridges the gap between complex network processes and user interactions.

Hackers might use network protocols in cyber attacks to exploit vulnerabilities and make way for malicious activity. They might abuse the HTTP, DNS, or NTP to carry out a distributed denial-of-service (DDoS) attack. In a DDoS attack, cybercriminals flood a network with fake HTTP requests, or DNS or NTP queries to prevent users from accessing a website or using a service.

Attackers might also manipulate network protocols to perform a man-in-the-middle (MitM) attack. In MitM attacks, hackers intercept or alter communication between the victim and the intended recipient of the data. They do it by exploiting weaknesses in protocols like ARP or tampering with SSL/TLS handshakes to decrypt and modify data.

Session hijacking is another type of attack where cybercriminals try to take control of an active communication session. They manipulate session-related data, such as HTTP cookies or session tokens, to impersonate legitimate users or gain unauthorized access.

Attackers might also use protocols like the HTTP, DNS, or FTP to exfiltrate stolen data from a compromised network without arousing suspicion. They encode or encrypt the data within these protocols to avoid detection.

FAQ

Who uses network protocols?

The internet functions by relying on network protocols, so each time you browse or search the web, you are using them without knowing it. However, you only interact with network protocols indirectly through the applications and services you use.

Only IT professionals, like developers, programmers, and network administrators, use network protocols extensively in their daily work to manage, develop, and secure networks. Hackers also use network protocols in their efforts to gain unauthorized access to systems and data, or spread malware.

What network protocols do routers use?

Routers use several network protocols to rout data packets between different networks. The Internet Protocol is the fundamental one that routers use for packet routing. It takes care of the addressing and forwarding aspects of data transfer. Routers also use the ICMP to manage the network and report errors. It allows the use of tools like ping and traceroute for diagnosing network connectivity issues.

The ARP is another key protocol that routers use for mapping IP addresses to MAC addresses within the local network. They also use the DHCP to automatically assign IP addresses, and the Internet Group Management Protocol (IGMP) to control multicast traffic.

This is not a finite list of network protocols that routers use, and the specific protocols a router supports may vary depending on the manufacturer, model, and intended use in the network.