> ## Documentation Index
> Fetch the complete documentation index at: https://docs.gcore.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Manage SSH keys

SSH key authentication provides a more secure alternative to [password login](/hosting/virtual-servers/manage/connect/linux-server/connect-to-linux-server-via-ssh) for Linux virtual servers. An SSH key pair consists of a private key stored locally and a public key deployed on the server. The server grants access only to connections that present the matching private key.

## Set up SSH key authentication

<Steps>
  <Step title="Generate a key pair">
    On the local machine (Linux, macOS, or Windows with OpenSSH), open a terminal and run:

    ```bash theme={null}
    ssh-keygen -t ed25519 -C "my-key"
    ```

    Press **Enter** to accept the default file path, or enter a custom path. The command creates two files:

    * `~/.ssh/id_ed25519` — the private key. Keep this file secure; do not share it with anyone.
    * `~/.ssh/id_ed25519.pub` — the public key. This is the file to copy to the server.

    The server username and IP address — needed in the next step — are available on the **Instructions** tab in the [Hosting portal](https://hosting.gcore.com/billmgr).
  </Step>

  <Step title="Copy the public key to the server">
    Run `ssh-copy-id` from the local machine while password access is still available:

    ```bash theme={null}
    ssh-copy-id -i ~/.ssh/id_ed25519.pub username@server_ip
    ```

    Replace `username` with the account name (typically `root`) and `server_ip` with the server's IP address.

    <Note>
      If `ssh-copy-id` is unavailable (Windows systems without OpenSSH 8.1 or later), append the public key manually. Log in to the server with a password, then run:

      ```bash theme={null}
      echo "public_key_content" >> ~/.ssh/authorized_keys
      chmod 600 ~/.ssh/authorized_keys
      ```

      Replace `public_key_content` with the full contents of the `id_ed25519.pub` file (a single long line starting with `ssh-ed25519`).
    </Note>
  </Step>
</Steps>

## Connect with an SSH key

With the public key on the server, connect using the private key:

```bash theme={null}
ssh -i ~/.ssh/id_ed25519 username@server_ip
```

If the key is stored in the default location (`~/.ssh/id_ed25519`), the `-i` flag can be omitted — the SSH client uses it automatically.

## Remove a public key

Open `~/.ssh/authorized_keys` on the server and delete the line containing the key to revoke:

```bash theme={null}
nano ~/.ssh/authorized_keys
```

Each line in the file represents one authorized key. Delete the line for the key to remove, then save the file. The removed key loses access on the next connection attempt.