What Is Telnet?
Telnet is a simple, text-based network protocol that is used for accessing remote computers over TCP/IP networks like the Internet. Telnet was created and launched in 1969 and, historically speaking, you can say that it was the first Internet.
In the old days, you had to physically walk to a server in order to access its data. This meant, among other things, that you had to spend some time arriving at the server’s location and then you had to wait for your turn to work with the server. Even if the server had the hardware power to do multiple things at the same time, you were blocked from using it at its full and you had to wait for others to finish their work first. In many circumstances you couldn’t even touch the actual server. You had to hand your card stack to an attendant and come back later for your printout.
Telnet brought extraordinary change. Using it meant you could simultaneously connect multiple users to a single server. In order to connect to the server, people only needed access to a terminal, which could be the simplest and cheapest computer available. This computer didn’t need to have powerful hardware, it only needed a network connection and a text based interface. Basically, their Telnet Client was like a Command Prompt that people could use in order to work with their servers. This brought a huge boost in productivity.
What are common uses for Telnet?
Telnet can be used to test or troubleshoot remote web or mail servers, as well as for remote access to MUDs (multi-user dungeon games) and trusted internal networks.
How Telnet works
Telnet is a type of client-server protocol that can be used to open a command line on a remote computer, typically a server. Users can utilize this tool to ping a port and find out whether it is open. Telnet works with what is called a virtual terminal connection emulator, or an abstract instance of a connection to a computer, using standard protocols to act like a physical terminal connected to a machine. FTP may also be used along with Telnet for users working to send data files.
Users connect remotely to a machine using Telnet, sometimes referred to as Telnetting into the system. They are prompted to enter their username and password combination to access the remote computer, which enables the running of command lines as if logged in to the computer in person. Despite the physical location of users, their IP address will match the computer logged in to rather than the one physically used to connect.
Uses of Telnet
Telnet can be used for a variety of activities on a server, including editing files, running various programs and checking email.
Some servers enable remote connections using Telnet to access public data to play simple games or look up weather reports. Many of these features exist for nostalgic fun or because they still have compatibility with older systems that need access to specific data.
Users are also able to connect to any software that utilizes text-based, unencrypted protocols via Telnet, from web servers to ports. Users can open a command prompt on the remote machine, type the word telnet and the remote machine’s name or IP address, and the telnet connection will ping the port to see if it is open or not. An open port will show a blank screen, while an error message that says the port is connecting means that it is closed.
Security
Telnet is not a secure protocol and is unencrypted. By monitoring a user’s connection, anyone can access a person’s username, password and other private information that is typed over the Telnet session in plaintext. With this information, access can be gained to the user’s device.
The advantages and disadvantages of the Telnet protocol
Since Telnet connections are practically standard TCP connections, the client can be employed to use or test other services that rely on TCP as a transport protocol. For example, with a simple request, you can check the functionality of an HTTP server or (as mentioned earlier) the status of an e-mail server. This versatility is enhanced by the fact that the connection protocol can be used across platforms. There are only a few devices that do not support the official IETF standard. Whether or not the client and server computers rely on the same operating system is also irrelevant. A further advantage of Telnet is that it allows unrestricted access to a controlled system’s resources if permission has been given.
The latter point, however, presents a high-security risk when combined with a previously unmentioned disadvantage: neither the connection setup nor the data transmission is encrypted when the Telnet protocol is used. All information you send can, therefore, be intercepted by third parties in plain text, including the login information required for remote access. This means that hackers won’t have much trouble taking over the system.
An overview of the advantages and disadvantages:
| Advantages | Disadvantages |
| Telnet client is versatile | Unencrypted data exchange |
| Can be used cross-platform | Full access makes it easier for hackers |
| Unlimited access to target resources | Only few servers can be reached via Telnet |
