SSH Protocol – What it is and what it is for

One of the most important tools when working on a server that does not have a graphical interface is undoubtedly the SSH protocol . 

This element is used daily by system workers and also by developers. It has enough potential to help us perform all kinds of functions on our server.

That said, in this post we will explain what SSH is, examples and characteristics, what an SSH server is for, and why it is the service most used by WebMasters , SysAdmins or DevOps workers, among others. 

  

Índice

  1. What is the SSH protocol and what are its characteristics?
  2. How does it work?
  3. Why use the SSH protocol?

What is the SSH protocol and what are its characteristics?

The letters SSH are the meaning of Secure Shell , which is a protocol that is used to operate servers remotely , offering the user all kinds of tasks therein.  

In connections made through SSH, all information circulates privately, so that alone makes it one of the safest means if we work on a server . 

To see its origins, we must go back a few years, exactly to 1995, when SSH-1 (its previous version) was developed by Tatu Ylönen in Helsinki. The main idea of ​​SSH was to be an effective replacement for other protocols that were more fashionable at the time, but much less secure, such as Telnet.  

The most notable features are the following:

  • The data we send and receive using SSH is always done using 128-bit encryption algorithms , so it is very difficult to decrypt it.   

  • It offers us the possibility of verifying that we are still connected to the same server as initially.

  • We have the possibility of using applications completely safely from the server command option, which will allow us to manage without any problem.

How does it work?

The operation is simple, we can summarize it in 6 steps that we leave you now:

  • You will have to initiate a TCP connection on port 22 of the service  (this is the port used by default in the protocol, although it can be modified).

  • A tab will appear in which you will be given the option to agree on the version of the protocol to use , as well as the encryption algorithm used to exchange the information. 

  • The server has two keys , one public and one private, and it is the first one that will be sent to you.

  • When you receive this key, you must compare it with the one you already have saved to verify that it is correct. The SSH protocol will ask you to confirm it the first time.  

  • Now, with the public key available, you must generate a random session key , and create a message that contains that key and the previously selected algorithm to encrypt all the information. 

  • If everything has gone well, the authentication will be ready , and all that remains is to log in to be able to communicate with the server. 

Why use the SSH protocol?

Having already analyzed one of the most popular protocols on the Internet, it is clear that, if you are looking to encrypt information and have a secure communication protocol, SSH is the best option for this.  

Everyone likes to do everything in the most secure way , and we are sure that using the SSH protocol will not clash when it comes to security.