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Understanding the Difference Between SSH vs. SSL


At the outset, SSL (Secure Socket Layer) and SSH (Secure Shell) may seem similar. They are both cryptographic protocols encrypt and secure data in transit, safeguarding connections. However, there are quite a few differences between SSL certificates and SSH, especially in terms of their intended purposes. In this article, we will dig deeper into these two cryptographic protocols, their features, and the SSL-SSH difference. 

SSH vs. SSL: The Definitions 


Developed by SSH Communications Security Ltd., SSH or Secure Shell is a cryptographic protocol. SSH aids in establishing secure connections and safe internet access to servers and network devices. This protocol enables users to remotely log in to another system (such as the website server) and issue and execute commands over a secure remote connection. 

It leverages public key cryptography, authentication, and encryption to establish a secure connection between devices, regardless of the security level of the underlying network infrastructure. By safeguarding the server and other network devices, SSH protects data, files, and other website resources from being compromised when they are accessed/ managed using a remote connection by authorized personnel such as system administrators. 

SSH helps in remote performing file transfer, command execution, etc., through secure connections even when the network is insecure. So, attackers will not be able to intercept or modify commands, sniff passwords, etc. 


SSL or Secure Socket Layer is a cryptographic protocol, which uses Public Key Encryption (PKI) to secure data in transmission, safeguarding its authenticity, integrity, and privacy. Transport Layer Security (TLS) protocols are used for encryption, and browsers have deprecated the outdated SSL protocols. Despite the minor differences, TLS and SSL are interchangeably used. 

SSL leverages digital certificates and PKI to encrypt HTTPS connections between the server and clients and all data in transit. By doing so, it ensures that the data is not tampered with or intercepted by malicious actors. It helps prevent man-in-the-middle attacks, impersonation, phishing attacks, eavesdropping, etc. 

It is implemented in diverse networked environments such as web browsers, emails, messaging, FTP, etc. SSL certificates have been mandatory for all websites since 2018, with browsers marking websites without them as Insecure. 

The Key Differences Between SSL and SSH

How do they work? 

One of the main differences between SSL and SSH is how they work. 

Using the client-server model, SSH creates a tunnel between two remote computers, enabling one to interact with the other's operating shell. SSH contains three layers - transport, authentication, and connection. For creating the tunnel, an SSH handshake is necessary. This starts with SSH version exchange and algorithm negotiation to establish a TCP connection, followed by an exchange of keys. An SSH tunnel is created, making the operating shell of the remote machine visible. Shell commands are securely exchanged between the systems. 

SSL uses digital signatures/ certificates and PKI to establish a trusting relationship between the server and the client. To this end, a full SSL/ TLS Handshake is necessary. SSL/ TLS Handshake starts with the client exchanging hello messages and SSL certificate verification. Upon verification of the certificate, the client sends the premaster secret (encrypted using the pre-shared public key), decrypted by the server using its private key. After the SSL/TLS Handshake is completed, information can be safely transmitted between the server and the client using encryption and hashing protocols. 


Another key SSH vs. SSL difference is that the SSL is a security protocol used to encrypt data in transmission and works based on digital certificates. At the same time, SSH is a remote network protocol used for securely managing and executing commands remotely by leveraging network tunneling. 

If a website owner/ system administrator wants to connect remotely to their website server and manage their WordPress site, they will leverage SSH. 

If they want to submit data on a frontend form, the server encrypts the form data using SSL protocols and moves the data between the browser and server. For instance, the credit card information submitted by a website user for completing a purchase would be transmitted to the server by breaking down and encrypting the fragments of information to ensure they are tamper-proof. One of the best ways to ensure user trust in the website is by installing an SSL certificate from reputed certificate providers like Entrust from Indusface.

Ports Used 

The other major difference between SSL and SSH is the ports that are used. SSH works on port 22, while SSL uses the more secure HTTPS port 443.  

Authentication Requirements 

The authentication requirements of the SSH key vs. SSL certificate are different. SSH has a three-stage authentication process - server authentication by the client, session key generation, and client authentication. Client authentication is especially important because the client will have privileged access to the server and can run commands remotely. With SSL, only server authentication is necessary. 


Despite the differences between SSL and SSH, they are not mutually exclusive; they are used in combination to create more robust security solutions. 

Published Thursday, July 28, 2022 7:32 AM by David Marshall
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