mirror of
https://github.com/alyraffauf/nixcfg.git
synced 2024-12-22 07:12:55 -05:00
97 lines
4.3 KiB
Markdown
97 lines
4.3 KiB
Markdown
# Hosts
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## Overview
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Host-specific configuration + common modules that aren't better expressed as options & flake outputs. All hosts are configured with [agenix](https://github.com/ryantm/agenix), [disko](https://github.com/nix-community/disko), and [nixhw](https://github.com/alyraffauf/nixhw).
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## Automatic Updates
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These hosts update themselves automatically, once a day, by rebuilding directly from one of this repository's branches, typically master.
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## Declarative WiFi Connections
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WiFi networks can be configured declaratiely in `wifi.nix` using `config.networking.networkmanager.ensureProfiles.profiles`, provided by nixpkgs. I also provide helper functions for common wifi security types.
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[nm2nix](https://github.com/janik-haag/nm2nix) can generate nix code for all WiFi networks currently configured in `/etc/NetworkManager/system-connections/` and `/run/NetworkManager/system-connections` with the following command:
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```bash
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sudo su -c "cd /etc/NetworkManager/system-connections && nix --extra-experimental-features 'nix-command flakes' run github:Janik-Haag/nm2nix | nix --extra-experimental-features 'nix-command flakes' run nixpkgs#nixfmt-rfc-style"
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```
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Secrets (passwords, certificates, and identities) are supported, but must be declared and available as variables with agenix. They will be replaced upon activation with `envsubst`.
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In short,
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1. Manually configure the WiFi network on one device.
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1. Export configuration to nix with `nm2nix`.
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1. Add secrets to `secrets/wifi.age` as variables (e.g. `MYPSK=1234567890`)
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1. Edit the code generated by `nm2nix` to reference `$MYPSK` instead of directly declaring the WPA password.
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1. Commit and push changes.
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1. Rebuild hosts as required to propogate your new WiFi configuration.
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## Provisioning New Devices
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1. Create `hosts/$HOSTNAME/default.nix` and other host-specific nix modules (e.g. `disko.nix`,`hardware.nix`, and `home.nix`).
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1. Add host to `nixosConfigurations` in `flake.nix`.
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1. (OPTIONAL) Generate a `cert.pem`, `key.pem`, and device ID for Syncthing with `syncthing -generate=$HOSTNAME`. Find the device ID in the generated `config.xml` and add it to `nixosModules/services/syncthing/default.nix`, encrypt the cert and key with agenix, and set them as appropriate in the host configuration.
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1. Install NixOS from this flake. Secrets will _not_ be available on first boot without a valid SSH private key.
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1. On a separate PC, copy the new system's public SSH key (`/etc/ssh/ssh_host_ed25519_key.pub`) to the host configuration (`secrets/publicKeys/root_$HOSTNAME.pub`).
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1. Add the new public key to `secrets/secrets.nix`, rekey all secrets with `agenix --rekey`, and push your changes to master.
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1. Rebuild the new system from git. Secrets will be automatically decrypted and immediately available in `/run/agenix/` for NixOS and `$XDG_RUNTIME_DIR/agenix/` for users.
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1. (OPTIONAL) Generate a new user SSH key and add it to `nixosModules/users/default.nix` in order to enable passwordless logins to other hosts.
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## Secure Boot
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1. Generate secure boot keys:
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```bash
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sudo nix run nixpkgs#sbctl create-keys
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```
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1. Enable lanzaboote in NixOS host configuration:
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```nix
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boot = {
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initrd.systemd.enable = true; # For automatic decryption with TPM.
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loader.systemd-boot.enable = lib.mkForce false; # Interferes with lanzaboote and must be force-disabled.
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lanzaboote = {
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enable = true;
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pkiBundle = "/etc/secureboot";
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};
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};
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```
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1. In UEFI, set secure boot to "setup mode" or erase platform keys.
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1. Enroll your secure boot keys:
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```bash
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sudo nix run nixpkgs#sbctl -- enroll-keys --microsoft
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```
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1. Reboot, make sure secure boot is enabled in UEFI.
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1. Check secure boot status with `bootctl status`:
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```bash
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System:
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Firmware: UEFI 2.70 (American Megatrends 5.17)
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Firmware Arch: x64
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Secure Boot: enabled (user)
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TPM2 Support: yes
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Measured UKI: yes
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Boot into FW: supported
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```
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1. If your root drive is encrypted with LUKS, you can have the TPM automatically decrypt it on boot:
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```bash
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sudo systemd-cryptenroll --tpm2-device=auto --tpm2-pcrs=0+2+7+12 --wipe-slot=tpm2 /dev/nvme0n1p2
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```
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Replace `/dev/nvme0n1p2` with your root partition.
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Check the [Linux TPM PCR Registry](https://uapi-group.org/specifications/specs/linux_tpm_pcr_registry/) for more details.
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**NOTE:** This requires a TPM2 module, devices with prior versions will not work.
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