SSH

in English: Secure Shell (SSH)

advancedwidespread

SSH is an encrypted channel through which you can securely log in to a remote computer and issue commands as if you were sitting in front of it.

In plain terms

Imagine laying an opaque, armored pipe between your computer and a remote server. What you write in one end comes out the other, but no one sees inside along the way, and no one can tamper with it. This is SSH: a standard by which two computers communicate encrypted over the open internet.

It is most often used for someone to control a computer remotely: typing commands, launching programs, copying files. Most servers behind websites, applications, and AI systems are managed this way, and virtually all Linux servers as well. These stand in data centers, with no screen or keyboard in front of them.

Unlike a remote desktop where you see the other machine's screen and click with a mouse: SSH provides a text command line by default. This makes it fast, functional even on weak connections, and easily automatable, which is why coding agents often work on remote machines through it.

How it works

Your machine (the client) contacts the remote machine (the server), typically on port 22, and they agree on which encryption method to use.
The server presents its own identification key. On the first connection, your machine asks whether you trust it; later, it warns you if the key has changed, as this may indicate someone is impersonating the server.
Two machines jointly create a one-time secret key to encrypt the entire conversation, ensuring the key itself never traverses the network.
Next, you verify your identity: with a password or, more securely, a key pair. The public half of the key pair is on the server, while the private half remains only on your device, which proves possession without revealing the key.
If everything is in order, the channel opens: you can run commands, copy files, or route traffic from other programs through it.

An everyday example

A small business online store runs on a rented server in a foreign data center. When the developer updates the site, they log in to the server via SSH from their own laptop and issue commands there. The same happens when they upload their code to GitHub: in the background, an SSH key often verifies that it is really them.

Who is affected

developerA daily work tool: you use it to log in to servers, upload code, and let the coding agent work on a remote machine. → Code

entrepreneur, executiveSSH keys leading to your company's servers are like safe keys: you must know who has them and ensure that access for departing employees and subcontractors is revoked.

industrial worker, engineerNetwork devices, industrial controllers, and embedded machines are often configured and maintained via SSH. → Industry

parent, student, teacherAnyone studying programming or IT will almost certainly encounter it with their first own server or Raspberry Pi project. → Education & Family

A common misconception

MythIf I use SSH, my server is automatically secure.

In realitySSH only protects the connection, not the two endpoints. Access can still be gained through a weak password, a stolen key or an unpatched server.

Limits and risks

Your secret key is like a house key: if someone copies it from your machine, they can log in in your name without you noticing. Therefore, protect it with a passphrase and never send it to anyone.
Automated programs continuously try SSH servers accessible from the internet, so it is advisable to disable password login and allow only key-based login.
If you grant an AI agent SSH access, it can do anything on the remote machine that the given user can do, so grant it only as much permission as the task requires.
If your computer warns you that the server key has changed, do not proceed without thinking: first investigate the cause, as the message may also indicate that someone is impersonating the server.

Similar, but not the same

VPN – A VPN typically redirects your computer's entire network traffic through an encrypted tunnel, whereas SSH provides access and a command line to a specific machine.
HTTPS – HTTPS encrypts traffic between the browser and websites, while SSH handles remote machine management and file copying.
Remote Desktop – A remote desktop shows the full screen of another machine in a mouse-controllable way, while SSH by default provides only a text command line.

Related concepts

Broader

Network protocol, Encryption, Remote access

Narrower

SSH-kulcs, SFTP, SSH tunnel

On the edge

Terminal, Parancssor, Szerver, Git, VPN

A brief history

SSH was created in 1995 by Finnish researcher Tatu Ylönen at the Helsinki University of Technology after an attack on the university network intercepted passwords. The version used today, SSH-2, was standardized by the IETF in 2006; the most widespread free implementation, OpenSSH, has existed since 1999.

Where things stand

At the end of 2026, SSH is the default tool for remote server management; the SSH client comes built into Windows, macOS, and Linux systems. Its new area of use is remote work by coding agents. The most widespread implementation, OpenSSH, already uses a key exchange by default that also resists quantum computers.

Status: 2026 November

In the news

Appears in 4 Agent Age stories; the curve shows weekly occurrence in the news magazine.

Malicious Claude Code extension in Cursor marketplace reportedly reaches 5,000 usersNov 2, 2026 · Code
Tampered Claude Code extension installed an SSH backdoor on about 5,000 machinesOct 30, 2026 · Agent Age
Trojanized Claude Code extension on Cursor marketplace delivered SSH backdoor to developer machinesOct 29, 2026 · Code
LiteLLM was poisoned using GitHub tokens leaked from Claude Code, attacker saysOct 26, 2026 · Code

Also known as

SSH · Secure Shell · ssh · SSH-protokoll · SSH-kapcsolat · SSH access · OpenSSH · Secure Shell (SSH)

Sources

This entry was machine-edited and has undergone machine expert review; the “In the news” section updates automatically from Agent Age stories.