server-security-wiki/secure-ssh.md

# Secure SSH

## Disable root

Edit `/etc/ssh/sshd_config` and set `PermitRootLogin no` or if you really need root access, e.g. for backups set `PermitRootLogin forced-commands-only`.

## Use Public Key Authentication

Create a new key pair on your client:

```
ssh-keygen -t ed25519 -a 100
```

Remember the path and password you choosed. Append the created public key from `/<your-path>/<key-name>.pub` on your client in the `/home/<user>/.ssh/authorized_keys` on your server. Alternatively you can use the command `ssh-copy-id` on your local client. For this command you can do the following:

```bash
ssh-copy-id -i /<your-path>/<key-name>.pub user@host
```

Now edit `/etc/ssh/sshd_config` on your server and set the following values:

```
PubkeyAuthentication yes
AuthorizedKeysFile .ssh/authorized_keys

PasswordAuthentication no
```

If you changed the path you can add the following to your `~/.ssh/config` file on your client:

```
Host <your-host-or-ip>
        User <the-server-username> # optional
        IdentityFile /<your-path>/<key-name>
        IdentitiesOnly yes # useful if you have problems when trying to login
```

## Apply Changes

To apply changes you made in the ssh config simply run `systemctl restart ssh.service` or `service ssh restart`.