Skip to main content

SSH in Linux: A Comprehensive Overview

SSH vs. FTP: A Comparative Overview

FeatureSSH (with SFTP)FTP
SecurityUses encryption to secure data transmission.Data, including passwords, is unencrypted.
Port UsageTypically uses a single port (22).Uses two ports (20 for data, 21 for control).
AuthenticationCan use passwords or public key authentication.Generally uses plaintext passwords.
Data IntegrityEnsures data integrity via cryptographic signatures.No built-in data integrity checks.
File Transfer CapabilitiesIntegrated with SFTP for secure file transfers.Primary purpose is for file transfers.
InteroperabilityWorks on almost all major OS platforms.Universal support on most platforms.

While FTP remains a significant protocol, especially for simple file transfers, SSH (and by extension SFTP) offers a secure, robust, and versatile solution for remote management and encrypted data transfers. As security concerns continue to rise, the preference towards encrypted and secure protocols like SSH is evident.

SSH vs. Open SSH

SSH (Secure Shell) is a protocol for securely accessing and managing systems over a potentially unsecured network. Tatu Ylönen, a Finnish researcher, originally developed it in 1995 in response to a password-sniffing attack at his university. The original implementation that Ylönen developed is often referred to as "SSH-1" or simply "SSH."

OpenSSH, on the other hand, is an implementation of the SSH protocol and is the most widely-used version today. Here are the key differences between Tatu Ylönen's original SSH and OpenSSH:

  1. Origins:

    • SSH: Developed by Tatu Ylönen in 1995. The original SSH software became proprietary with the founding of SSH Communications Security.
    • OpenSSH: Started as a fork of the free version of SSH in 1999 by the OpenBSD team, led by Theo de Raadt, to create a fully open-source version.
  2. Licensing:

    • SSH: The original SSH was initially released as freeware, but later versions became proprietary.
    • OpenSSH: It is open-source and freely available. It is released under the BSD license, which allows for free use, modification, and distribution.
  3. Features and Security:

    • SSH: The earlier versions, especially SSH-1, had several cryptographic weaknesses.
    • OpenSSH: Over time, OpenSSH has integrated various security enhancements and features, making it more secure and versatile. It also deprecated the use of SSH-1 due to its vulnerabilities.
  4. Adoption:

    • SSH: While it was popular in its early days, the proprietary versions have been mostly replaced in the community by OpenSSH.
    • OpenSSH: This has become the de facto standard implementation of the SSH protocol due to its open-source nature, wide distribution, and consistent updates. Most Linux distributions and even other operating systems, including macOS and Windows (through Windows Subsystem for Linux and other means), now use or support OpenSSH.
  5. Development and Maintenance:

    • SSH: The commercial version continues to be developed and maintained by SSH Communications Security.
    • OpenSSH: Actively developed and maintained by the OpenBSD project, which prioritizes security and code clarity.

While both SSH (as conceived by Tatu Ylönen) and OpenSSH serve the same primary purpose of secure communication, they differ in their origins, licensing, features, and adoption. OpenSSH, due to its open-source nature and continuous development, has become the standard choice for SSH implementation in the modern tech ecosystem.

Which Distros Have SSH Installed

Not all Linux distributions come with SSH pre-installed. However, most mainstream Linux distributions, especially server editions, either come with SSH pre-installed or provide it in their default repositories for easy installation.

  • Ubuntu Server comes with the OpenSSH server package pre-installed, while the desktop edition comes with the OpenSSH client pre-installed, but not the server.
  • CentOS and Fedora server editions usually come with OpenSSH server and client installed by default.
  • Debian server installations often include OpenSSH server, but minimal installations might not.
  • Some lightweight or security-focused distributions might not have SSH by default, as they aim to minimize the attack surface or to remain as lean as possible.

If SSH is not installed, it can easily be added using the distribution's package manager, such as apt, yum, or pacman.

What Can You Do Next 🙏😊

If you liked the article, consider subscribing to Cloudaffle, my YouTube Channel, where I keep posting in-depth tutorials and all edutainment stuff for software developers.

YouTube @cloudaffle