How to Configure an SSH Key on an Existing Server

SSH lets you manage a server remotely from the command line, with the connection encrypted through port 22.

If the server is already deployed, you add the key from the section SSH Keys of the subscription, without recreating it.

👍 What you get

An active SSH key on a server already up and running, and the private key in your possession to connect securely.

❗️ Activating the key restarts the server

Unlike configuring it during setup, activating an SSH key on an existing server restarts the machine and generates a new password.

Do it in a window where you can accommodate that restart, not in full production.

How the key pair works

SSH uses two pieces that go together: the public key stays on the server and you keep the private key. The private one is what identifies you when connecting, so it isn't shared. You can find more details in How to configure an SSH key on a new server.

Item	Where it lives	What it's for
Public key	On the server	Verifies who connects
Private key	On your computer	Identifies you when connecting; not shared

Before you start

• Be registered on the Plenit platform and have permission to manage servers.
• Have a server deployed in a subscription of Servers.
• Be able to tolerate a server restart during activation.

Step 1. Go to the SSH Keys section

1. Go to the subscription of Servers from its card.
2. In the right-hand side submenu, open SSH Keys.
3. Click Create SSH Key.

{/* 📸 CAPTURE 1 · side submenu with "SSH Keys" and the Create SSH Key button */}

Access to the SSH Keys section with the Create SSH Key button

Step 2. Create and activate the key

1. Enter a name for the key.
2. Check Generate a new key.
3. Select the servers where you want to activate it.
4. Click Continue.

The platform warns that activating the key restarts the server and generates a new password. Click Confirm to continue. The restart and key generation begin.

{/* 📸 CAPTURE 2 · key dialog with "Generate a new key" and the selection of servers */}

SSH key registration and selection of the servers where it will be activated

❗️ Save the private key and password: they are shown only once

During the process, two pieces of data appear that cannot be consulted again. Copy and save them as soon as you see them:

• The private key SSH. Click Confirm after copying it.
• The new password of the server. Click Confirm after copying it.

Step 3. Connect with the key

Save the private key in a file and protect it: SSH rejects a key with permissions that are too open.

On Linux or macOS:

# Restrict the key permissions
chmod 600 ~/.ssh/plenit-srv01

# Connect (username and IP of your server)
ssh -i ~/.ssh/plenit-srv01 <username>@<SERVER-IP>

On Windows, with the OpenSSH client from PowerShell:

icacls "C:\Users\<your-user>\.ssh\plenit-srv01" /inheritance:r /grant:r "%USERNAME%:R"
ssh -i "C:\Users\<your-user>\.ssh\plenit-srv01" <username>@<SERVER-IP>

📘 The user depends on the image

The username for connecting is determined by the server's operating system. If you're not sure, confirm it based on the deployed image.

If something does not fit

Symptom	Likely cause	What to do
The server restarted without warning anyone	Activation restarts the machine	Plan activation in a maintenance window
You don't have the private key or the password	They were shown only during the process and were not saved	Create a new key; another password will be generated
SSH rejects the key due to permissions	The private key is accessible to other users	Apply chmod 600 (Linux) or icacls (Windows)