What is SSH? A plain-English guide
What SSH is, how it works, and the difference between SSH keys and passwords — plus how Servor uses SSH only to set up a server.
SSH (Secure Shell) is the standard way to log in to a remote server and run commands on it over an encrypted connection. If you've ever managed a VPS, a cloud instance, or a Raspberry Pi from your laptop, you've almost certainly used SSH. This guide explains what SSH is, how it works, and how SSH keys differ from passwords — then shows where SSH fits into Servor.
What is SSH, exactly?
SSH is a network protocol that gives you a secure, text-based session on a remote machine. Everything you type and everything the server sends back is encrypted, so no one between you and the server can read it. It replaced older tools like Telnet, which sent everything — including passwords — in plain text.
In practice, "using SSH" usually means opening a terminal and typing something like:
ssh user@your-server.example.comOnce connected, you get a shell on the remote machine and can run commands as if you were sitting in front of it.
How does SSH work?
SSH uses a client (your computer) and a server (the machine you're
connecting to, running an SSH daemon, usually sshd on port 22). When you
connect:
The client and server agree on encryption
They negotiate a shared secret so the whole session is encrypted. This happens before you ever type a password or send a key.
The server proves its identity
The server presents its host key. Your client remembers it (the "known hosts" prompt the first time you connect), so it can warn you if the server ever changes unexpectedly.
You prove your identity
You authenticate — with a password, or with an SSH key pair (recommended). Once accepted, your session starts.
SSH keys vs. passwords
You can log in over SSH two main ways. They are not equally safe.
| Password | SSH key pair | |
|---|---|---|
| What you send | A secret you type | A cryptographic proof — your private key never leaves your machine |
| Brute-force risk | High — bots hammer port 22 all day | Practically none |
| Convenience | Type it every time | Log in with no prompt once set up |
| Best for | Quick one-off access | Everything, especially servers exposed to the internet |
How SSH keys work
An SSH key comes in two halves:
- A private key, which stays on your computer and is never shared.
- A public key, which you copy to the server (into
~/.ssh/authorized_keys).
When you connect, the server challenges your client to prove it holds the private key that matches the stored public key — without ever transmitting the private key itself. That's why key-based auth is both more secure and more convenient than passwords.
Disable password login once keys work
On a public server, a common hardening step is to set
PasswordAuthentication no in sshd_config after confirming your key works.
This stops password brute-force attempts entirely.
How Servor uses SSH
Here's the important part if you're using Servor: SSH is only used once, to set up a server. Day-to-day, Servor does not run your commands over SSH.
When you add a server, Servor can use SSH to probe the machine, discover a few basics, and install a lightweight agent. From that point on, everything — the web terminal, running commands, and resource metrics — goes through that agent, not SSH. Add a server in Servor
This is why a server can show as unreachable even when SSH still works: it means the agent isn't connected. The fix is Repair the agent, not reconnecting over SSH.
You don't have to keep port 22 open
Because execution runs through the agent, you can lock down or close inbound SSH after setup and Servor keeps working normally.
Frequently asked questions
Is SSH secure?
Yes. SSH encrypts the entire session, so credentials and commands can't be read in transit. Security depends on how you configure it — using SSH keys instead of passwords and keeping your server patched are the two biggest wins.
What port does SSH use?
Port 22 by default. Some administrators change it to reduce automated
scanning noise, but changing the port is not a substitute for real hardening like
key-based authentication.
Do I need to know SSH to use Servor?
No. You only need to run one install command once. After that, you manage the server from the browser through the web terminal and commands.
What's the difference between SSH and the Servor web terminal?
Both give you a shell on the server. SSH connects directly from your computer over port 22. The web terminal runs in your browser and goes through the Servor agent — no SSH client, keys, or open port required on your end.
My server works over SSH but Servor says "unreachable" — why?
That almost always means the agent is down, not SSH. Servor stopped using SSH after setup, so it can't reach the machine until the agent reconnects. See Repair the agent and connection issues.
Can I use SSH keys with Servor?
Yes — for the initial setup step, Servor connects like any SSH client. After the agent is installed, keys are no longer part of day-to-day use.
See also
- Add a server — install the agent in one command
- Repair the agent — fix an "unreachable" server
- Web terminal — a shell in your browser
- Connection issues — troubleshoot connectivity
- Glossary — key terms explained