depot/third_party/nixpkgs/nixos/doc/manual/configuration/ssh.section.md

Secure Shell Access

Secure shell (SSH) access to your machine can be enabled by setting:

{
  services.openssh.enable = true;
}

By default, root logins using a password are disallowed. They can be disabled entirely by setting to "no".

You can declaratively specify authorised public keys for a user as follows:

{
  users.users.alice.openssh.authorizedKeys.keys =
    [ "ssh-ed25519 AAAAB3NzaC1kc3MAAACBAPIkGWVEt4..." ];
}