How an intruder attacks SSH
Brute Force
© Lead Image © imaginariumphoto, 123RF.com
Sometimes the only way to break into an SSH server is through brute force – and yes, there are tools for that.
One particular Linux service needs no introduction: Secure Shell (SSH) is synonymous with logging into remote Linux devices of all varieties. You can use SSH to log into a Raspberry Pi, a mail server, a web server, or even embedded Linux devices such as those running Internet of Things (IoT) applications.
SSH emerged in the 1990s, when it became clear that the unencrypted Telnet was not suitable for communication on the open Internet. SSH version 1 was popular for years, but experts eventually began to warn that it had its own security problems. SSH version 2 was a major rewrite, due to the numerous issues that plagued version 1, including vulnerability to man-in-the-middle attacks. In the Linux world, the SSH software of choice for both client and server is called OpenSSH [1].
This article looks at some of the approaches attackers and ethical hackers use to compromise SSH servers. I will also look at how to prevent a common type of attack against SSH servers. It should go without saying: Only use the tools discussed in this article on servers that you own or explicitly have permission to test against. A number of these approaches could cause downtime or ultimately lock you out of the target SSH instance.
[...]
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
US / Canada
UK / Australia
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.
News
-
Linux Kernel 6.17 is Available
Linus Torvalds has announced that the latest kernel has been released with plenty of core improvements and even more hardware support.
-
Kali Linux 2025.3 Released with New Hacking Tools
If you're a Kali Linux fan, you'll be glad to know that the third release of this famous pen-testing distribution is now available with updates for key components.
-
Zorin OS 18 Beta Available for Testing
The latest release from the team behind Zorin OS is ready for public testing, and it includes plenty of improvements to make it more powerful, user-friendly, and productive.
-
Fedora Linux 43 Beta Now Available for Testing
Fedora Linux 43 Beta ships with Gnome 49 and KDE Plasma 6.4 (and other goodies).
-
USB4 Maintainer Leaves Intel
Michael Jamet, one of the primary maintainers of USB4 and Thunderbolt drivers, has left Intel, leaving a gaping hole for the Linux community to deal with.
-
Budgie 10.9.3 Now Available
The latest version of this elegant and configurable Linux desktop aligns with changes in Gnome 49.
-
KDE Linux Alpha Available for Daring Users
It's official, KDE Linux has arrived, but it's not quite ready for prime time.
-
AMD Initiates Graphics Driver Updates for Linux Kernel 6.18
This new AMD update focuses on power management, display handling, and hardware support for Radeon GPUs.
-
AerynOS Alpha Release Available
With a choice of several desktop environments, AerynOS 2025.08 is almost ready to be your next operating system.
-
AUR Repository Still Under DDoS Attack
Arch User Repository continues to be under a DDoS attack that has been going on for more than two weeks.