Hello folks, what is the default username and password for nixos for raspberry pi?

Help
1

What is the default username and password for the most recent raspberry pi image? i see root and nixos in /etc/passwd but i don’t know the password. i also don’t have a micro hdmi yet to use.

arm image: Hydra - nixos:trunk-combined:nixos.sd_image.aarch64-linux
nix.dev : Installing NixOS on a Raspberry Pi — nix.dev documentation

2

if you followed the guide and ran nixos-rebuild switch then your username is whatever you set in the config:

let
  user = "guest";
  password = "guest";

You can run sudo -i to get a root shell as stated in the nix.dev tutorial if you haven’t yet installed. But I gather you’re trying to ssh in since you don’t have a HDMI cable? in any case, sudo -i should work for what you need

3

that is if you have a monitor connected to the raspberrypi.

power it on.

You should be greeted with a fresh shell!

you will be automatically logged in. i have not logged in to it at all. i am trying to ssh into it because i don’t have a monitor and a micro hdmi cable.

4

right, sshd isn’t started by default. I’m not sure if the serial console (UART) is enabled by default either but that would require a different cable. Worth a shot if you have one.

5

have a look at this NixOS on a Raspberry Pi: creating a custom SD image with OpenSSH out of the box | Roberto Frenna - you can probably enable sshd by default by building a custom sd image
Here’s the repo: GitHub - Robertof/nixos-docker-sd-image-builder: Build custom SD images of NixOS for your Raspberry Pi (or any other supported AArch64 device) in 5-20 minutes.
I think I followed this approach some time ago and it worked. Oh, and according to that repp

since (NixOS 20.09), OpenSSH is now enabled by default in pre-built NixOS SD images

Just a matter of copying in the right key pair

If you would like to continue the installation from a different machine you can use activated SSH daemon. You need to copy your ssh key to either /home/nixos/.ssh/authorized_keys or /root/.ssh/authorized_keys (Tip: For installers with a modifiable filesystem such as the sd-card installer image a key can be manually placed by mounting the image on a different machine). Alternatively you must set a password for either root or nixos with passwd to be able to login.

6

it seems its sshd is enabled because it asks me to enter username and password. (even though the guide instructs about enabling ssh, inferring that it is not enabled )

7

Yep, you are correct. sd image have it enabled and you’re clearly seeing it work. That nix.dev doc should be updated perhaps. See my edits above. It’s just a matter of mounting the sd card and copying your keys

8

i cannot access /root - permission denied. i will try putting my keys in /home/nixos

9

it is still asking for password even if i explicitly indicate a private key.
i could disable password authentication in /etc/ssh/ssh_config, but that is a symlink to configuration in /nix/store.
i don’t know exactly what these hashed things are but i am guessing that they are generated using nixos-rebuild switch, which i can’t do since i can’t even authenticate.
am i right?

10

did you load up the keys for “nixos” user?

The installer starts with a “nixos” user to allow installation, so add the SSH key to
that user. Note that the key is, at the time of writing, put in /etc/ssh/authorized_keys.d

It’s not ideal, but at this point I’d try making a custom sd image. Strange that it’s still asking for a password

11

it still did not work. i will try to create a custom sd image.

12

Cool. Let us know how it goes or if you need any assistance. I’ve found it’s easy with flakes but works without too, of course. Just a matter of remembering the commands (or just having a good reference or two) . Here’s a few resources:
GitHub - lucernae/nixos-pi: How to install NixOS on raspberry PI (no flakes)
GitHub - rjpcasalino/pie (flakes)
myme.no - NixOS: On Raspberry Pi 3B

13

putting the public key in /home/nixos/.ssh/authorized_keys actually works.
I made a little mistake in the directory that last time.
Thanks

2 Likes
14

Could someone clarify - how exactly I should put this authorized_keys to SD media?
I flash it with the pre-made minimal .iso image, so no rw partitions exist there by default, right?
Where should I put the file then?

EDIT:
I’m about SD media for x86_64.

15

Here’s some config for references for ssh with (replace variables in UPPERCASE with your own):
- password authentication disabled
- ed25519 keys accepted only
- non-default 22 port

  users = {
    users."${USER_NAME}" = {
      initialPassword  = USER_PASSWORD;
      openssh.authorizedKeys.keys = [
        USER_SSH_PUBLIC_KEY
      ];
    };
  };

  /*
    SSH
    - disable password authentication
    - ed25519 keys only
    - non-default 22 port
  */
  services.openssh = {
    enable = true;
    ports = [ 
      SSH_PORT
    ];

    settings = {
      PasswordAuthentication = false;
      KbdInteractiveAuthentication = false;
      PermitRootLogin = lib.mkForce "no";
      KexAlgorithms = [
        # ssh-ed25519
        "curve25519-sha256"
        "curve25519-sha256@libssh.org"
      ];
    };
  };

Full config (example is for a pi-hole): GitHub - JimJ92120/nixos-pi-hole: A NixOS image build for Raspberry Pi with Pi-hole.