Difference between SSH and Telnet

Last Updated : 06 Sep, 2024

SSH and Telnet are two protocols commonly used to log on remotely and perform configuration and management tasks on devices that are connected via a network. Although both types of wireless networks differ slightly in general function, they have more differences in the aspects of the security features and operations. Due to the strong security measures implemented in its protocols, SSH is the most popular in modern networking.

Telnet is much older than SSH and is currently considered outdated as it does not encrypt the data transmitted between the user and the system and is therefore prone to security-related threats. Knowing the distinctions between SSH and Telnet is mainly important to avoid confusion and make the right decision when it comes to framing the network.

SSH or Secure SHell

SSH or Secure SHell is now the only major protocol to access network devices and servers over the internet. SSH was developed by SSH Communications Security Ltd., it is a program to log into another computer over a network, execute commands in a remote machine, and move 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 the information in encrypted form which provides confidentiality and security of the data over an unsecured network such as the internet.
Once the data for communication is encrypted using SSH, it is extremely difficult to decrypt and read that data, so our passwords also become secure to travel on a public network.
SSH also uses a public key for the authentication of users accessing a server and it is a great practice providing us extreme security. SSH is mostly 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 play back the traffic or hijack the connection when encryption is enabled.
When using ssh’s login (instead of rlogin) the entire login session, including the transmission of password, is encrypted. Therefore it is almost impossible for an outsider to collect passwords.

Installation of the OpenSSH client and server applications is simpler.

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-server

And that’s pretty much it! Simple no?

Telnet

Telnet is the joint abbreviation of Telecommunications and Networks and it is a networking protocol best known for UNIX platform. Telnet uses the port 23 and it was designed specifically for local area networks.

Telnet is famous for being the original Internet when the Net first launched in 1969 and was built to be form of remote control to manage mainframe computers from distant terminals. In those original days of large mainframe computers, telnet enabled research students and 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 networking 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 in some use today by purists.

Telnet is not a secure communication protocol because it does not use any security mechanism and transfers the data over network/internet in a plain-text form including the passwords and so any one can sniff the packets to get that important information.

There are no authentication policies & data encryption techniques used in telnet causing huge security threat that is why telnet is no longer used for accessing network devices and servers over public network.

On a Ubuntu(a famous and my personal favorite linux distro.) We can install the telnet server with following commands:

$sudo apt-get install xinetd telnetd

The service should be fired-up automatically once the installation is done. Your may also check the service status if required using:

$sudo /etc/init.d/xinetd status

To Telnet an IP:

$telnet serverip

If you would like to change its ports, you’ll 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

Right now it might looking like some tedious and wacky terminal commands but if you try to run them once on your terminal, trust me you’ll find it extremely easy!

Just like SSH, Telnet is also apparently just a dull and boring terminal screen but with some unimaginable features.

Differences Between SSH and Telnet

Feature	SSH (Secure Shell)	Telnet (Telecommunication Network)
Security	SSH encrypts the data transmitted, ensuring confidentiality and integrity.	Telnet transmits data in plain text, making it vulnerable to eavesdropping and man-in-the-middle attacks.
Authentication	SSH uses strong authentication methods like password-based or key-based authentication.	Telnet uses basic authentication methods, often without encryption, making it insecure.
Default Port	22	23
Data Encryption	Data is encrypted, providing secure communication over the network.	No encryption, data is transmitted in plain text.
Usage	Commonly used for secure remote administration of network devices and systems.	Typically used for remote management of devices but is now largely obsolete due to security risks.
Protocol	SSH is a protocol that provides secure, encrypted channels over an unsecured network.	Telnet is an older protocol that provides unencrypted communication over a network.
File Transfer	SSH supports file transfer using SCP (Secure Copy) or SFTP (Secure File Transfer Protocol).	Telnet does not natively support file transfer.
Operating System Support	Widely supported across various operating systems (Unix, Linux, Windows).	Supported on many systems but is now deprecated and replaced by more secure alternatives.

Lastly, there are some SSH clients, the software that you can use to setup a connection with the SSH server available for all the major operating systems and tablet operating systems.

Mac OS X & Linux: built-in, available in Terminal
Windows: PuTTY, others
Android: JuiceSSH, others
iOS: Prompt, others

If you want to connect your Windows PC with a Linux PC then you need software called ‘PuTTY’.

After installation it’ll look a lot like this:

PuTTy

Conclusion

SSH and Telnet are both used to manage the devices remotely but there is a huge difference in terms of providing the security to network. SSH is recommended in present day networking since it has relative high encryption and authentication aspects hence enhancing the security of the network. Although Telnet is easier to use and more easy to implement, it is deemed insecure for most of the applications and has not been in use as widely as its replacement protocols. To achieve proper evaluation of the protocols it is vital to comprehend their strengths and weaknesses to ensure that their best fit in meeting the required networking functionality is employed.