Networking Protocols You Must Know

An established set of guidelines that govern how data is transferred between various devices connected to the same network is known as a network protocol. In essence, it makes it possible for connected devices to interact with one another despite any variations in their internal workings, organizational structures, or aesthetics.

Below is the list of different network protocols which are a must-know if you are in the IT industry either as a professional or student.

Transmission Control Protocol(TCP)

A common protocol for network communication at the transport layer specifies how to connect and exchange data streams. It is a fundamental network protocol that ensures message delivery. Additionally, it assures that packets are delivered to the destination host in the same order as they were sent by the sender and guarantees packet order delivery.

User Datagram Protocol(UDP)

A datagram is a brief message that is sent using an unreliable transport layer protocol from the Internet protocol. UDP is a significant protocol that can be used instead of TCP to create low-latency connections without keeping track of the connection state.

File Transfer Protocol(FTP)

FTP is used to send and receive files. The default port for the network protocol used for file transfers between clients and servers is port 21. In accordance with the permissions granted by the server administrator, the FTP clients can be used to browse the server’s designated directory and modify the files.

FTP Servers – FileZilla FTPS, IIS FTPS, vsftpd, Pro FTPD, Pure FTPd

FTP Clients – FileZilla, WinSCP, FireFTP

SSH File Transfer Protocol (SFTP)

The standard protocol of FTP which is more secure in terms of data security.

Secure Shell(SSH)

A network protocol that uses cryptography to connect clients and servers securely over unsecured networks. The most popular servers and clients are listed below, along with the default port number for SSH communication, which is 22.

Example: Openssh, Dropbear, etc.


A client and a server can communicate bidirectionally and interactively using this TCP/IP networking protocol over a terminal. 23 is the default port for Telnet communication. Also known as Teletype Network, this type of network is primarily utilized on terminals for computer-to-computer communication. Telnet only allows for the clear text transmission or transmission of unencrypted messages.

Internet Control Message Protocol(ICMP)

When network issues prevent the delivery of an IP packet, network devices use a network layer protocol to send error messages and operational information. Those packets are called ICMP transmitted using ICMP protocol. The ICMP messages are sent as datagrams, with an IP header enclosing the message data and being primarily used for packet failure and error detection.

Address Resolution Protocol (ARP)

The communication protocol is used to map an IP address to a physical machine address in the computer network. It’s used to discover the MAC address associated with the given internet address i.e. IPv4 address.

Reverse Address Resolution Protocol (RARP)

It is a TCP/IP network layer communication protocol used by devices or clients to request IP addresses from the computer network.

Secure Socket Layer (SSL)

An encrypted link between a web server and a web browser is established using a security protocol. It ensures that all communication between endpoints is encrypted and secure. It stops common security attacking methods like sniffing, man-in-the-middle attacks, and eavesdropping.

Transport Layer Security (TLS)

It is a communication protocol that encrypts all the data which is being transmitted in the network.

Remote Desktop Protocol (RDP)

A remote user can safely add a graphical interface to the desktop of another computer to exchange encrypted messages thanks to a proprietary protocol created by Microsoft. The remote user can operate the system much like a local user would.

Examples: Remote Desktop, rdesktop, Remmina, VNC connect, Teamviewer, etc.

Dynamic Host Configuration Protocol (DHCP)

The connectionless network management protocol used by the DHCP server on UDP/IP dynamically assign an IP address to any device or network node so they can exchange IP traffic with other endpoints.

It does not incur the costs associated with manually allocating IP addresses to nodes connected via computer networks. Within the same network, the DHCP server assigns an IP address to the connecting node.

Network Time Protocol (NTP)

A networking standard is used to synchronize clocks across different devices, and systems in a network. It allows for the extremely precise synchronization of computer clocks, ensuring greater accuracy of local time with respect to Coordinated Universal Time (UTC).

Point-to-Point Protocol (PPP)

Data link layer communication protocol is an encapsulation protocol used to establish a direct connection between two nodes for transferring datagram between the connected nodes.

Domain Naming System (DNS)

The main job of DNS protocol is to resolve domain name systems to an IP address. A user cannot remember all IP addresses of servers hence those are referenced with domain names and stored in the DNS server.

Examples: Google DNS, Cloudflare, OpenDNS, etc.

Hey, If you would like to know about different types of security vulnerabilities in DNS systems Please Check Top 10 DNS Attacks.

Simple Mail Transfer Protocol (SMTP)

The standard TCP/IP application layer protocol is used for email transmission. The default port used for SMTP communication is 25.

SMTP Servers – Postfix, Sendmail, Haraka
SMTP Clients – Mozilla Thunderbird, Outlook

Hypertext Transfer Protocol (HTTP)

The World Wide Web’s underlying application layer protocol establishes the rules for message exchanges between a Web server and a browser or other HTTP client using port 80 as the default.

HTTP Servers – Apache HTTP Server, Nginx, Jetty, IIS, Apache Tomcat, LiteSpeed Web Server, etc.
HTTP Clients – Browsers

Hypertext Transfer Protocol Secure (HTTPS)

It is the secure version of HTTP. All web traffic between the browser and server is encrypted with SSL/TLS to provide data security. Port 443 is used by HTTPS service.

Post Office Protocol 3 (POP3)

An application layer protocol is used by email clients to retrieve emails from a mail server.

POP3 Servers – Dovecot
POP3 Clients – Mozilla Thunderbird, Outlook

Internet Message Access Protocol (IMAP)

It is a method for retrieving emails from mail servers that keeps a copy of each message on the mail server and is used by email clients. It makes sure that emails are synced between various devices while keeping a copy of each email on every connected device. Other connected devices will be affected by an action taken on one. The used port is 143.

Real-Time Streaming Protocol (RTSP)

Application-level network control protocol used to transfer real-time audio, video, and data over the internet. rstp:// protocol is used.

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