SSH and SSL are both cryptographic protocols and have similar names, but they are used in different circumstances. In this article, we will discuss the differences between SSH and SSL and will discuss which one you should use.
SSH (Secure Shell) is an encryption protocol used to secure connections within a network. SSH is mostly used to log in and execute remote commands from a client to a server.
SSH uses port 22 to transfer data and comes in two major versions called SSH-1 and SSH-2. It was originally devised for Unix servers and is the main tool for administrating such servers, but is used for Windows servers as well.
After establishing an SSH (shell) session, you can type commands and execute them on the server computer, as if you are there.
SSH is considered a secure way to transfer data within a network, despite having certain vulnerabilities. Edward Snowden’s leaks suggested that governments can in certain cases decode SSH as well.
SSL (Secure Sockets Layer) is an encryption protocol used for securing data transfer within a network, including the internet. It was developed first by Netscape in 1995 as a way of securing the connection between a browser and a web server.
SSL was replaced by TLS in 1999, although the term ‘SSL’ is still used to refer to TLS technology and other web-encryption concepts. For example, a certificate that allows websites to move to an HTTPS protocol is often called an ‘SSL certificate’, while it actually uses TLS 1.3 for securing the connection.
So, SSH and SSL are both cryptographic protocols to secure a network connection. What is the difference between the two?
The main difference between the two protocols is their actual use-cases. SSH is used to secure a remote connection to a server and send secure commands to the server. SSH also asks for user authentication to establish the connection.
SSL is used for securing the exchange of information between two sources and is used to secure the Internet as well as secure email and text-messaging exchanges. Normally SSL does not ask for login details or user authentication. Instead, it uses something named an ‘X.509 digital certificate for authentication.
So SSH is focused on securing networks based upon tunnels whilst SSL is focused on securing network connections based upon digital certificates.
SSH also has a lot of built-in functionalities to accommodate password authentication and sending commands. You can do this using SSL as well, but they are considered something besides SSL rather than a function of it.
So, can we change the roles and use SSL for sending commands or SSH for securing an Internet connection? Probably with some changes and tools development this could be done. But the main difference between these two protocols is that they have evolved throughout the years to serve their specific purposes and different tools have been devised to facilitate this.
So to decide between SSL and SSH you need to look at what you want to use them for.
As we mentioned SSH and SSL use-cases barely overlap. So to decide which one you need to use, you need to look at what you want to use them for.
If you want to connect to your Unix or Windows server and execute a command, you will probably use an SSH client to do so. If you want to secure a connection between a browser and a website, and exchange confidential information such as credit card details, you should use an SSL certificate do it.
It is also wrong to say SSH is more secure than SSL or vice-versa. They both are trusted security protocols and both have vulnerabilities. But they are used in different circumstances and their alternatives are different from each other.