SSH Vs. SSL – The Technical Differences Explained

Deciphering the Distinctions: A Comprehensive Comparison of SSH vs SSL/TLS

Many of us get confused when talking about SSH Vs. SSL protocols. It happens because both of these protocols rely on public key cryptography. But both of these protocols SSL and SSH are different. One of the main differences that sets them apart is how both of these protocols operate.

SSL works on public key infrastructure (PKI). PKI is a framework that involves Certificate Authorities (CAs), which issue a digital certificate that establishes trust between two parties. But it’s not the case when considering the SSH protocol. SSH protocol does not use digital certificates; instead, it requires private and public keys, commonly known as SSH keys, to establish a secure connection.

Other notable dissimilarities between these two protocols come into light when you notice the functionality each protocol provides. SSH protocol allows you to log in securely to another computer (remote machine) by creating a secure tunnel. This secure tunnel is created once the authentication of the user is successful. The main functionality of SSL protocol is to encrypt data in transmission between a client (browser) and a server, and it does not require any authentication from the user.

In this article, we will examine SSL vs SSH in great depth. And for a better understanding of the topic (SSH vs SSL), let’s explore the technical difference between these two protocols in a tabular format. Here’s the table:

The Key Differences of SSH and SSL

Benchmark	SSH	SSL
Protocol Type	Cryptographic Network Protocol	Security Protocol
Function	Connects you to a remote machine to issue commands securely.	It lets you securely transmit data between a server and a client (browser).
Port Number	Port 22	Port 443
Authentication Method	Username/Password or SSH Key	Digital Certificates
Implementation	To implement this protocol, SSH software should be installed on both server and client.	To implement this protocol, an SSL certificate is needed on the server side.

What is SSH?

Secure Shell (SSH) is a type of cryptographic network protocol that allows a user to connect or communicate with a remote computer securely. SSH protocol is for securing computer networks.

Recommended: Secure Shell Protocol (SSH) – Everything you need to know

Secure Shell protocol was initially developed or created for UNIX-based computers but is now available on Windows. The primary purpose of developing this protocol was to find a replacement for Telnet and other Unix shell protocols, such as Berkeley Remote Shell (rsh), which were quite insecure as they were transferring data as plain text, and no encryption was done.

The reason why the SSH protocol is quite secure and preferred over its predecessors is that the SSH protocol encrypts the data in transmission and protects it from network snooping attacks while allowing secure logins by requiring client authentication.

To accomplish all this, SSH creates an SSH tunnel between two remote computers. And once this tunnel is established, the remote system shell is visible, and the shell commands can be safely transmitted or sent across the connection (as they are in encrypted format); this process is commonly known as SSH handshake.

Working of SSH Protocol

To understand the working of SSH protocol in a better way, let’s review its working in the form of multiple steps.

• Step 1: The user requests the server to initiate an SSH session after connecting to it.
• Step 2: Upon receiving the user’s request, the server accepts it and sends a public key as confirmation (proof) of its identity.
• Step 3: The user verifies that public key to authenticate the web server’s identity, and if the verification is successful, a session key is generated.
• Step 4: The user enciphers the generated session key and transmits it to the server.
• Step 5: The server decrypts the ciphered session key using its unique private key.
• Step 6: The user and server now share the same symmetric session key, which is employed to secure all communication during the session.

Note: A session key is like a symmetric key that performs both the operations: encryption and decryption. But always remember that this key is only valid for one session.

What do you use SSH for?

There are literally “n” number of reasons for using the SSH protocol. Let’s explore some of the most prominent ones, such as:

• Secure remote login: SSH offers robust and latest authentication methods, such as two-factor authentication and public key authentication. Users can use these methods to securely connect to a machine remotely.
  
• Secure file transfer: The data in transition is encrypted because of encryption techniques. This makes it extremely hard for unauthorized entities to either intercept or view the contents of the data packet.
• Port forwarding: SSH’s port forwarding or tunneling feature provides access to resources remotely but in a secure manner. This feature is of utmost importance because without it, connecting to remote resources would have been impossible due to network security policies or firewall restrictions.

• Network management: SSH acts as a practical tool for managing network devices remotely, such as routers and switches. Using SSH enables a secure way to configure and monitor these devices.
• Decreases Workload: The script automation feature of SSH allows administrators to execute scripts remotely, which in turn reduces the workload on administrators and improves the overall system management efficiency.

What is SSL?

The full form of SSL is Secure Socket Layer. SSL protocol is a common security protocol responsible for protecting data transmission between two parties, such as a web browser and a server. This protocol uses encryption and authentication to accomplish this task.

By using digital certificates and PKI, SSL is able to create encrypted HTTPS connections. Once the SSL connection is created, you can securely transmit sensitive information, such as credit card details and personal information, without worrying about man-in-the-middle attacks or eavesdropping.

People often use both of these terms – SSL and TLS, interchangeably, and this could happen because of any of the two reasons mentioned below:

• People believe both to be the same.
• The popularity of the term “SSL.”

It doesn’t matter what’s the reason for understanding both terms to be the same, but it’s not 100% true or correct. Let me take a moment to clear this myth. TLS is an upgraded version of SSL 3.0 and can provide more security against modern vulnerabilities and cyber attacks.

This is one of the reasons that many browsers are opting for either TLS 1.2 or 1.3. TLS 1.2 provides advanced encryption functions or techniques, such as ECC and AEAD cipher blocks. Whereas TLS 1.3 consists of all the features provided by TLS 1.2 and, in addition, it also provides downgrade attack prevention. So, stop searching for SSH vs TLS, if your aim is to get exact information regarding SSH vs SSL.

Working of SSL Protocol

To understand the working of SSL protocol in a better way, let’s review its working in the form of multiple steps.

• Step 1: The user sends a “Hello” message to a secured SSL site.
• Step 2: Upon receiving the user’s Hello, the server answers by sending the SSL certificate that contains a public key.
• Step 3: The user authenticates the public key so that the domain owner’s identity can be authenticated, and if the authentication is successful, a session key is produced.

• Step 4: The user enciphers the generated session key and transmits it to the server.
• Step 5: The server decrypts the ciphered session key using its unique private key.
• Step 6: The user and server now send a “Finished” message encrypted with the secret session key to each other before the completion of the SSL handshake process.
• Step 7: Every communication between the server and the client is encrypted and protected now.

What do you use SSL for?

There are a vast number of reasons for using SSH protocol. Let’s explore some of the most prominent ones, such as:

• Secure online transactions: Using SSL along with the SSL interception technique ensures secure transmission of sensitive data, such as information regarding social security numbers and online purchases.
  
• Authentication: SSL can authenticate the identity of a server, even before we start the transmission of data packets. This particular part holds huge importance, as encryption will be useless if the other party is not genuine or is just imitating to be a trusted entity. 
• Confidentiality: The data transmitted is encrypted using robust encryption algorithms that makes it tough for attackers or malicious actors to access or even understand the encrypted data. Hence, maintaining the confidentiality of the data.

Conclusion

SSH, or Secure Shell, is quite similar to SSL in a way that both of these protocols are PKI based, and both form encrypted communication tunnels. But, even though there are various differences between both of these protocols, such as:

• SSL uses the combination of both types of encryption algorithms – symmetric and asymmetric. This allows SSL to provide data confidentiality. But SSH doesn’t use both encryption algorithms; it just uses symmetric key encryption algorithms to provide data confidentiality.
• SSH provides protection against DNS spoofing and data manipulation, but SSL provides protection against identity theft and MiTM attacks.

To cut a long story short, SSL is for securing internet connections between websites and their visitors; SSH is for running commands via remote access.

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