Introduction to TELNET Last Updated : 15 Jul, 2025 Comments Improve Suggest changes Like Article Like Report TELNET stands for Teletype Network. It is a client/server application protocol that provides access to virtual terminals of remote systems on local area networks or the Internet. The local computer uses a telnet client program and the remote computers use a telnet server program. In this article, we will discuss every point about TELNET. What is Telnet?TELNET is a type of protocol that enables one computer to connect to the local computer. It is used as a standard TCP/IP protocol for virtual terminal service which is provided by ISO. The computer which starts the connection is known as the local computer. The computer which is being connected to i.e. which accepts the connection known as the remote computer. During telnet operation, whatever is being performed on the remote computer will be displayed by the local computer. Telnet operates on a client/server principle. History of TELNETThe Telnet protocol originated in the late 1960s, it was created to provide remote terminal access and control over mainframes and minicomputers. Initially, it was designed to be a simple and secure method of connecting to a remote system. This protocol allowed users to access remote computers using a terminal or command-line interface. Over time, Telnet’s use has diminished due to security concerns, and alternatives like SSH are now preferred for secure remote management Logging in TELNETThe logging process can be further categorized into two parts: Local LoginRemote Login1. Local Login Whenever a user logs into its local system, it is known as local login. Local LoginThe Procedure of Local Login Keystrokes are accepted by the terminal driver when the user types at the terminal.Terminal Driver passes these characters to OS.Now, OS validates the combination of characters and opens the required application.2. Remote Login Remote Login is a process in which users can log in to a remote site i.e. computer and use services that are available on the remote computer. With the help of remote login, a user is able to understand the result of transferring the result of processing from the remote computer to the local computer. Remote Login in LoggingThe Procedure of Remote LoginWhen the user types something on the local computer, the local operating system accepts the character.The local computer does not interpret the characters, it will send them to the TELNET client.TELNET client transforms these characters to a universal character set called Network Virtual Terminal (NVT) characters and it will pass them to the local TCP/IP protocol Stack.Commands or text which are in the form of NVT, travel through the Internet and it will arrive at the TCP/IP stack at the remote computer.Characters are then delivered to the operating system and later on passed to the TELNET server.Then TELNET server changes those characters to characters that can be understandable by a remote computer.The remote operating system receives characters from a pseudo-terminal driver, which is a piece of software that pretends that characters are coming from a terminal.The operating system then passes the character to the appropriate application program.Network Virtual Terminal(NVT)NVT (Network Virtual Terminal) is a virtual terminal in TELNET that has a fundamental structure that is shared by many different types of real terminals. NVT (Network Virtual Terminal) was created to make communication viable between different types of terminals with different operating systems. Network Virtual Terminal(NVT) in TelnetHow TELNET Works?Client-Server InteractionThe Telnet client initiates the connection by sending requests to the Telnet server.Once the connection is established, the client can send commands to the server.The server processes these commands and responds accordingly.Character FlowWhen the user types on the local computer, the local operating system accepts the characters.The Telnet client transforms these characters into a universal character set called Network Virtual Terminal (NVT) characters.These NVT characters travel through the Internet to the remote computer via the local TCP/IP protocol stack.The remote Telnet server converts these characters into a format understandable by the remote computer.The remote operating system receives the characters from a pseudo-terminal driver and passes them to the appropriate application program3.Network Virtual Terminal (NVT)NVT is a virtual terminal in Telnet that provides a common structure shared by different types of real terminals.It ensures communication compatibility between various terminals with different operating systems.TELNET CommandsCommands of Telnet are identified by a prefix character, Interpret As Command (IAC) with code 255. IAC is followed by command and option codes. The basic format of the command is as shown in the following figure : TELNET Command FormatFollowing are some of the important TELNET commands: Character Decimal Binary Meaning WILL251111110111. Offering to enable. 2. Accepting a request to enable. WON'T252111111001. Rejecting a request to enable. 2. Offering to disable. 3. Accepting a request to disable. DO25311111101`1. Approving a request to enable. 2. Requesting to enable. DON'T254111111101. Disapproving a request to enable. 2. Approving an offer to disable. 3. Requesting to disable. Following are some common options used with the telnet: Code Option Meaning 0BinaryIt interprets as 8-bit binary transmission.1EchoIt will echo the data that is received on one side to the other side.3Suppress go aheadIt will suppress go ahead signal after data.5StatusIt will request the status of TELNET.6Timing markIt defines the timing marks.8Line widthIt specifies the line width.9Page sizeIt specifies the number of lines on a page.24Terminal typeIt set the terminal type.32Terminal speedIt set the terminal speed.34Line modeIt will change to the line mode.Uses of TELNETRemote Administration and ManagementNetwork DiagnosticsUnderstanding Command-Line InterfacesAccessing Bulletin Board Systems (BBS)Automation and ScriptingAdvantages of TELNETIt provides remote access to someone's computer system.Telnet allows the user for more access with fewer problems in data transmission.Telnet saves a lot of time.The oldest system can be connected to a newer system with telnet having different operating systems.Disadvantages of TELNETAs it is somehow complex, it becomes difficult to beginners in understanding.Data is sent here in form of plain text, that's why it is not so secured.Some capabilities are disabled because of not proper interlinking of the remote and local devices.Modes of OperationDefault Mode: If no other modes are invoked then this mode is used. Echoing is performed in this mode by the client. In this mode, the user types a character and the client echoes the character on the screen but it does not send it until the whole line is completed.Character Mode: Each character typed in this mode is sent by the client to the server. A server in this type of mode normally echoes characters back to be displayed on the client's screen.Line Mode: Line editing like echoing, character erasing, etc. is done from the client side. The client will send the whole line to the server.ConclusionTelnet is a client/server application protocol that allows remote access to virtual terminals via local area networks or the internet. Telnet's use has decreased due to security concerns, with protocols such as SSH chosen for safe remote management. Telnet is still useful for remote administration, network diagnostics, instructional purposes, and interacting with legacy systems. Comment More infoAdvertise with us I itskawal2000 Follow Improve Article Tags : Computer Networks Similar Reads Computer Network Tutorial A Computer Network is a system where two or more devices are linked together to share data, resources and information. These networks can range from simple setups, like connecting two devices in your home, to massive global systems, like the Internet. Below are some uses of computer networksSharing 6 min read Computer Network BasicsBasics of Computer NetworkingA computer network is a collection of interconnected devices that share resources and information. These devices can include computers, servers, printers, and other hardware. Networks allow for the efficient exchange of data, enabling various applications such as email, file sharing, and internet br 10 min read Types of Computer NetworksA computer network is a system that connects many independent computers to share information (data) and resources. The integration of computers and other different devices allows users to communicate more easily. It is a collection of two or more computer systems that are linked together. A network 7 min read Introduction to InternetComputers and their structures are tough to approach, and it is made even extra tough when you want to recognize phrases associated with the difficulty this is already utilized in regular English, Network, and the net will appear to be absolutely wonderful from one some other, however, they may seem 10 min read Types of Network TopologyNetwork topology refers to the arrangement of different elements like nodes, links, or devices in a computer network. Common types of network topology include bus, star, ring, mesh, and tree topologies, each with its advantages and disadvantages. In this article, we will discuss different types of n 11 min read Network DevicesNetwork devices are physical devices that allow hardware on a computer network to communicate and interact with each other. Network devices like hubs, repeaters, bridges, switches, routers, gateways, and brouter help manage and direct data flow in a network. They ensure efficient communication betwe 9 min read What is OSI Model? - Layers of OSI ModelThe OSI (Open Systems Interconnection) Model is a set of rules that explains how different computer systems communicate over a network. OSI Model was developed by the International Organization for Standardization (ISO). The OSI Model consists of 7 layers and each layer has specific functions and re 13 min read TCP/IP ModelThe TCP/IP model is a framework that is used to model the communication in a network. It is mainly a collection of network protocols and organization of these protocols in different layers for modeling the network.It has four layers, Application, Transport, Network/Internet and Network Access.While 7 min read Difference Between OSI Model and TCP/IP ModelData communication is a process or act in which we can send or receive data. Understanding the fundamental structures of networking is crucial for anyone working with computer systems and communication. For data communication two models are available, the OSI (Open Systems Interconnection) Model, an 4 min read Physical LayerPhysical Layer in OSI ModelThe physical Layer is the bottom-most layer in the Open System Interconnection (OSI) Model, responsible for the physical and electrical transmission of data. It consists of various network components such as power plugs, connectors, receivers, cable types, etc. The physical layer sends data bits fro 4 min read Types of Network TopologyNetwork topology refers to the arrangement of different elements like nodes, links, or devices in a computer network. Common types of network topology include bus, star, ring, mesh, and tree topologies, each with its advantages and disadvantages. In this article, we will discuss different types of n 11 min read Transmission Modes in Computer Networks (Simplex, Half-Duplex and Full-Duplex)Transmission modes also known as communication modes, are methods of transferring data between devices on buses and networks designed to facilitate communication. They are classified into three types: Simplex Mode, Half-Duplex Mode, and Full-Duplex Mode. In this article, we will discuss Transmission 6 min read Types of Transmission MediaTransmission media is the physical medium through which data is transmitted from one device to another within a network. These media can be wired or wireless. The choice of medium depends on factors like distance, speed, and interference. In this article, we will discuss the transmission media. In t 9 min read Data Link LayerData Link Layer in OSI ModelThe data link layer is the second layer from the bottom in the OSI (Open System Interconnection) network architecture model. Responsible for the node-to-node delivery of data within the same local network. Major role is to ensure error-free transmission of information. Also responsible for encoding, 4 min read What is Switching?Switching is the process of transferring data packets from one device to another in a network, or from one network to another, using specific devices called switches. A computer user experiences switching all the time for example, accessing the Internet from your computer device, whenever a user req 5 min read Virtual LAN (VLAN)Virtual LAN (VLAN) is a concept in which we can divide the devices logically on layer 2 (data link layer). Generally, layer 3 devices divide the broadcast domain but the broadcast domain can be divided by switches using the concept of VLAN. A broadcast domain is a network segment in which if a devic 7 min read Framing in Data Link LayerFrames are the units of digital transmission, particularly in computer networks and telecommunications. Frames are comparable to the packets of energy called photons in the case of light energy. Frame is continuously used in Time Division Multiplexing process. Framing is a point-to-point connection 6 min read Error Control in Data Link LayerData-link layer uses the techniques of error control simply to ensure and confirm that all the data frames or packets, i.e. bit streams of data, are transmitted or transferred from sender to receiver with certain accuracy. Using or providing error control at this data link layer is an optimization, 4 min read Flow Control in Data Link LayerFlow control is design issue at Data Link Layer. It is a technique that generally observes the proper flow of data from sender to receiver. It is very essential because it is possible for sender to transmit data or information at very fast rate and hence receiver can receive this information and pro 4 min read Piggybacking in Computer NetworksPiggybacking is the technique of delaying outgoing acknowledgment temporarily and attaching it to the next data packet. When a data frame arrives, the receiver waits and does not send the control frame (acknowledgment) back immediately. The receiver waits until its network layer moves to the next da 5 min read Network LayerNetwork Layer in OSI ModelThe Network Layer is the 5th Layer from the top and the 3rd layer from the Bottom of the OSI Model. It is one of the most important layers which plays a key role in data transmission. The main job of this layer is to maintain the quality of the data and pass and transmit it from its source to its de 5 min read Introduction of Classful IP AddressingClassful IP addressing is an obsolete method for allocating IP addresses and dividing the available IP address space across networks. It was used from 1981 to 1993 until the introduction of CIDR (Based on Prefixes rather than classes). Classful method categorizes IP addresses into five classes (A, B 10 min read Classless Addressing in IP AddressingThe Network address identifies a network on the internet. Using this, we can find a range of addresses in the network and total possible number of hosts in the network. Mask is a 32-bit binary number that gives the network address in the address block when AND operation is bitwise applied on the mas 7 min read What is an IP Address?Imagine every device on the internet as a house. For you to send a letter to a friend living in one of these houses, you need their home address. In the digital world, this home address is what we call an IP (Internet Protocol) Address. It's a unique string of numbers separated by periods (IPv4) or 14 min read IPv4 Datagram HeaderIP stands for Internet Protocol and v4 stands for Version Four (IPv4). IPv4 was the primary version brought into action for production within the ARPANET in 1983. IP version four addresses are 32-bit integers which will be expressed in decimal notation. In this article, we will discuss about IPv4 da 4 min read Difference Between IPv4 and IPv6IPv4 and IPv6 are two versions of the system that gives devices a unique address on the internet, known as the Internet Protocol (IP). IP is like a set of rules that helps devices send and receive data online. Since the internet is made up of billions of connected devices, each one needs its own spe 7 min read Difference between Private and Public IP addressesIP Address or Internet Protocol Address is a type of address that is required to communicate one computer with another computer for exchanging information, file, webpage, etc. Public and Private IP address are two important parts of device identity. In this article, we will see the differences betwe 6 min read Introduction To SubnettingSubnetting is the process of dividing a large network into smaller networks called "subnets." Subnets provide each group of devices with their own space to communicate, which ultimately helps the network to work easily. This also boosts security and makes it easier to manage the network, as each sub 8 min read What is Routing?The process of choosing a path across one or more networks is known as Network Routing. Nowadays, individuals are more connected on the internet and hence, the need to use Routing Communication is essential.Routing chooses the routes along which Internet Protocol (IP) packets get from their source t 10 min read Network Layer ProtocolsNetwork Layer is responsible for the transmission of data or communication from one host to another host connected in a network. Rather than describing how data is transferred, it implements the technique for efficient transmission. In order to provide efficient communication protocols are used at t 9 min read Transport LayerTransport Layer in OSI ModelThe transport layer, or layer 4 of the OSI model, controls network traffic between hosts and end systems to guarantee full data flows. It is positioned between the network and session layers in the OSI paradigm. The data packets must be taken and sent to the appropriate machine by the network layer. 5 min read Transport Layer ProtocolsThe transport layer is the fourth layer in the OSI model and the second layer in the TCP/IP model. The transport layer provides with end to end connection between the source and the destination and reliable delivery of the services. Therefore transport layer is known as the end-to-end layer. The tra 9 min read What is TCP (Transmission Control Protocol)?Transmission Control Protocol (TCP) is a connection-oriented protocol for communications that helps in the exchange of messages between different devices over a network. It is one of the main protocols of the TCP/IP suite. In OSI model, it operates at the transport layer(Layer 4). It lies between th 5 min read User Datagram Protocol (UDP)User Datagram Protocol (UDP) is a Transport Layer protocol. UDP is a part of the Internet Protocol suite, referred to as UDP/IP suite. Unlike TCP, it is an unreliable and connectionless protocol. So, there is no need to establish a connection before data transfer. The UDP helps to establish low-late 10 min read Session Layer & Presentation LayerSession Layer in OSI modelThe Session Layer is the 5th layer in the Open System Interconnection (OSI) model which plays an important role in controlling the dialogues (connections) between computers. This layer is responsible for setting up, coordinating, and terminating conversations, exchanges, and dialogues between the ap 6 min read Presentation Layer in OSI modelPresentation Layer is the 6th layer in the Open System Interconnection (OSI) model. This layer is also known as Translation layer, as this layer serves as a data translator for the network. The data which this layer receives from the Application Layer is extracted and manipulated here as per the req 4 min read Secure Socket Layer (SSL)SSL or Secure Sockets Layer, is an Internet security protocol that encrypts data to keep it safe. It was created by Netscape in 1995 to ensure privacy, authentication, and data integrity in online communications. SSL is the older version of what we now call TLS (Transport Layer Security).Websites us 10 min read PPTP Full Form - Point-to-Point Tunneling ProtocolPPTP Stands for Point-to-Point Tunneling Protocol is a widely used networking protocol designed to create a secure private connection over a public network like the internet. It is Developed by Microsoft and other tech companies in the 1990s It is one of the first protocols used for Virtual Private 5 min read Multipurpose Internet Mail Extension (MIME) ProtocolMIME (Multipurpose Internet Mail Extensions) is a standard used to extend the format of email messages, allowing them to include more than just text. It enables the transmission of multimedia content such as images, audio, video, and attachments, within email messages, as well as other types of cont 4 min read Application LayerApplication Layer in OSI ModelThe Application Layer of OSI (Open System Interconnection) model, is the top layer in this model and takes care of network communication. The application layer provides the functionality to send and receive data from users. It acts as the interface between the user and the application. The applicati 5 min read Client-Server ModelThe Client-Server Model is a distributed architecture where clients request services and servers provide them. Clients send requests to servers, which process them and return the results. Clients don’t share resources among themselves but depend on the server. Common examples include email systems a 5 min read World Wide Web (WWW)The World Wide Web (WWW), often called the Web, is a system of interconnected webpages and information that you can access using the Internet. It was created to help people share and find information easily, using links that connect different pages together. The Web allows us to browse websites, wat 6 min read Introduction to Electronic MailIntroduction:Electronic mail, commonly known as email, is a method of exchanging messages over the internet. Here are the basics of email:An email address: This is a unique identifier for each user, typically in the format of [email protected] email client: This is a software program used to send, 4 min read What is a Content Distribution Network and how does it work?Over the last few years, there has been a huge increase in the number of Internet users. YouTube alone has 2 Billion users worldwide, while Netflix has over 160 million users. Streaming content to such a wide demographic of users is no easy task. One can think that a straightforward approach to this 4 min read Protocols in Application LayerThe Application Layer is the topmost layer in the Open System Interconnection (OSI) model. This layer provides several ways for manipulating the data which enables any type of user to access the network with ease. The Application Layer interface directly interacts with the application and provides c 7 min read Advanced TopicsWhat is Network Security?Network security is defined as the activity created to protect the integrity of your network and data. Network security is the practice of protecting a computer network from unauthorized access, misuse, or attacks. It involves using tools, technologies, policies, and procedures to ensure the confide 8 min read Computer Network | Quality of Service and MultimediaQuality of Service (QoS) is an important concept, particularly when working with multimedia applications. Multimedia applications, such as video conferencing, streaming services, and VoIP (Voice over IP), require certain bandwidth, latency, jitter, and packet loss parameters. QoS methods help ensure 7 min read Authentication in Computer NetworkPrerequisite - Authentication and Authorization Authentication is the process of verifying the identity of a user or information. User authentication is the process of verifying the identity of a user when that user logs in to a computer system. There are different types of authentication systems wh 4 min read Encryption, Its Algorithms And Its FutureEncryption plays a vital role in today’s digital world, serving a major role in modern cyber security. It involves converting plain text into cipher text, ensuring that sensitive information remains secure from unauthorized access. By making data unreadable to unauthorized parties, encryption helps 10 min read Introduction of Firewall in Computer NetworkA firewall is a network security device, either hardware or software-based, which monitors all incoming and outgoing traffic and based on a defined set of security rules, it accepts, rejects, or drops that specific traffic. It acts like a security guard that helps keep your digital world safe from u 7 min read MAC Filtering in Computer NetworkThere are two kinds of network Adapters. A wired adapter allows us to set up a connection to a modem or router via Ethernet in a computer whereas a wireless adapter identifies and connects to remote hot spots. Each adapter has a distinct label known as a MAC address which recognizes and authenticate 10 min read Wi-Fi Standards ExplainedWi-Fi stands for Wireless Fidelity, and it is developed by an organization called IEEE (Institute of Electrical and Electronics Engineers) they set standards for the Wi-Fi system. Each Wi-Fi network standard has two parameters : Speed - This is the data transfer rate of the network measured in Mbps 4 min read What is Bluetooth?Bluetooth is used for short-range wireless voice and data communication. It is a Wireless Personal Area Network (WPAN) technology and is used for data communications over smaller distances. This generation changed into being invented via Ericson in 1994. It operates within the unlicensed, business, 6 min read Generations of wireless communicationWe have made very huge improvements in wireless communication and have expanded the capabilities of our wireless communication system. We all have seen various generations in our life. Let's discuss them one by one. 0th Generation: Pre-cell phone mobile telephony technology, such as radio telephones 2 min read Cloud NetworkingCloud Networking is a service or science in which a company’s networking procedure is hosted on a public or private cloud. Cloud Computing is source management in which more than one computing resources share an identical platform and customers are additionally enabled to get entry to these resource 11 min read PracticeTop 50 Plus Networking Interview Questions and Answers for 2024Networking is defined as connected devices that may exchange data or information and share resources. A computer network connects computers to exchange data via a communication media. Computer networking is the most often asked question at leading organizations such Cisco, Accenture, Uber, Airbnb, G 15+ min read Top 50 TCP/IP Interview Questions and Answers 2025Understanding TCP/IP is essential for anyone working in IT or networking. It's a fundamental part of how the internet and most networks operate. Whether you're just starting or you're looking to move up in your career, knowing TCP/IP inside and out can really give you an edge.In this interview prepa 15+ min read Top 50 IP Addressing Interview Questions and AnswersIn today’s digital age, every device connected to the internet relies on a unique identifier called an IP Address. If you’re aiming for a career in IT or networking, mastering the concept of IP addresses is crucial. In this engaging blog post, we’ll explore the most commonly asked IP address intervi 15+ min read Last Minute Notes for Computer NetworksComputer Networks is an important subject in the GATE Computer Science syllabus. It encompasses fundamental concepts like Network Models, Routing Algorithms, Congestion Control, TCP/IP Protocol Suite, and Network Security. These topics are essential for understanding how data is transmitted, managed 14 min read Computer Network - Cheat SheetA computer network is an interconnected computing device that can exchange data and share resources. These connected devices use a set of rules called communication protocols to transfer information over physical or wireless technology. Modern networks offer more than just connectivity. Enterprises 15+ min read Like