Introduction to TELNET – GeeksforGeeks

If you’ve been using a Linux distribution for quite some time and are no longer a Linux newbie, you may have come across terms like SSH and telnet. They are quite similar when it comes to facilities they provide, but did SSH come into play when Telnet already existed?

SSH or Secure SHell

SSH or

Secure SHell is now the single primary protocol for accessing network devices and servers over the Internet. SSH was developed by SSH Communications Security Ltd., is a program for logging into another computer over a network, executing commands on a remote machine, and moving files from one machine to another.

  • It provides strong authentication and secure communications over insecure channels
  • .

  • SSH runs on port 22 by default; however, it can be easily changed. SSH is a very secure protocol because it shares and sends information in encrypted form that provides confidentiality and security of data over an unsecured network such as the Internet.
  • Once data for communication is encrypted using SSH, it is extremely difficult to decrypt and read that data, so our passwords also become secure for travel on a public network.
  • SSH also uses a public key for authentication of users accessing a server and is a great practice that provides us with extreme security. SSH is mainly used in all popular operating systems like Unix, Solaris, Red-Hat Linux, CentOS, Ubuntu, etc.
  • SSH protects a network from attacks such as IP spoofing, IP source routing, and DNS spoofing. An attacker who has managed to take over a network can only force ssh to disconnect. He or she cannot replay traffic or hijack the connection when encryption is enabled.
  • When using ssh slogin (instead of rlogin), the entire login session, including password transmission, is encrypted; therefore, it is almost impossible for an outsider to collect passwords.

Installing OpenSSH client and server applications is easier.

To install it

on your Ubuntu system

, use this command at a terminal prompt: $sudo apt-get update $sudo apt install openssh-client

To install the OpenSSH server application and related support files, use this command at a terminal prompt:

$sudo apt-get update $sudo apt install openssh-serverAnd

that’s it! Simple, isn’t it?

Telnet Telnet

is the

joint abbreviation for Telecommunications and Networking and is a best-known network protocol for the UNIX platform. Telnet uses port 23 and was designed specifically for local area networks.

  • Telnet is famous for being the original Internet when the Net was first launched in 1969 and was built to be a form of remote control for managing mainframe computers from distant terminals. In those original days of large mainframes, telnet allowed students and research professors to “log in” to the university mainframe from any terminal in the building.
  • This remote login saved researchers hours of walking each semester. While telnet pales in comparison to modern network technology, it was revolutionary in 1969, and telnet helped pave the way for the eventual World Wide Web in 1989. While telnet technology is very old, it is still used today by purists.
  • Telnet is not a secure communication protocol because it does not use any security mechanism and transfers the data over the network/internet in plain text form, including passwords, so anyone can sniff the packets to get that important information.
  • There are no authentication policies and data encryption techniques used in telnet that cause a major security threat, so telnet is no longer used to access network devices and servers over public networks.

On an Ubuntu (a famous and my favorite Linux distribution). We can install the telnet server with the following commands:

$sudo apt-get install xinetd

telnetd The service should start automatically once the installation is done. You can also check the service status if necessary using

: $sudo /etc/init.d/xinetd status

For Telnet an IP

: $telnet serverip

If you want to change its ports, you will need to edit

/etc/services with the line: $telnet 23/tcp Once changed, restart

to apply the changes with:

$sudo /etc/init.d/xinetd restart

At this point it may seem like a tedious and extravagant terminal command, but if you try to run them once your terminal is turned on, trust me, you will find it extremely easy!

Like SSH, Telnet

is also seemingly just a boring and boring terminal screen, but with some unimaginable features.

Differences between

SSH and Telnet SSH is more secure compared to Telnet SSH encrypts data while Telnet

  1. sends data in plain text
  2. SSH uses

  3. a public key for authentication, whereas Telnet does not use any
  4. SSH authentication

  5. adds a bit more overhead to bandwidth compared to
  6. Telnet

  7. Telnet has been replaced by SSH in almost all uses
  8. SSH and Telnet

  9. commonly serve the same purpose
  10. SSH

  11. allows remote command execution, while Telnet does not support this feature.
  12. SSH is based on external terminal emulation software, while Telnet includes built-in terminal emulation.

Finally, there are some SSH clients, the software you can use to set up a connection to the SSH server available for all major operating systems and tablet operating systems.

  • Mac OS X and Linux: built-in, available in Windows Terminal
  • : PuTTY, other

  • Android: JuiceSSH,
  • other

  • iOS: Prompt, others
  • If you want to connect your Windows PC with a Linux PC, you need software called ‘

  • PuTTY

‘. After installation, it will look a lot like this:

PuTTy

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