SSH

    Specify a key when connecting 

    ssh -i ~/.ssh/privatekey user@remoteaddr.tld

    RouterOS specific notes

    MikroTik routers have SSH enabled by default. To enable passwordless login, I had to upload my public key to the "File" section and import it using the following command:

    /user ssh-keys import public-key-file=id_rsa.pub user=admin

    Troubles

    WARNING: UNPROTECTED PRIVATE KEY FILE!

    Happened to me because I'd downloaded the key files. The error prevents the file from being used. The solution is to chmod it to 600 like this.1

    chmod 600 ~/.ssh/privatekey

    This will allow read+write only from the user.

    Refs

    1 https://tecadmin.net/ssh-with-private-key-warning-unprotected-private-key-file/