fips/packaging/nixos

NixOS Packaging

NixOS module and flake outputs for FIPS.

Quick Start (flake consumers)

Add fips as a flake input and enable the service:

# flake.nix
{
  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
    fips = {
      url = "github:jmcorgan/fips";
      inputs.nixpkgs.follows = "nixpkgs";
    };
  };

  outputs = { self, nixpkgs, fips, ... }@inputs: {
    nixosConfigurations.myhost = nixpkgs.lib.nixosSystem {
      specialArgs = { inherit inputs; };
      modules = [
        ./configuration.nix
        fips.nixosModules.default     # ← import the module
        {
          services.fips.enable = true; # ← enable the daemon
        }
      ];
    };
  };
}

Apply with:

sudo nixos-rebuild switch --flake .#myhost

Options

Option	Type	Default	Description
services.fips.enable	bool	false	Enable the FIPS mesh network daemon
services.fips.package	package	pkgs.fips	The fips package (provided via overlay)
services.fips.configFile	path	shipped default	Default fips.yaml used to seed /var/lib/fips/fips.yaml on first run
services.fips.openFirewall	bool	true	Open UDP 2121 + TCP 8443
services.fips.dns.enable	bool	true	Route .fips queries to the fips DNS responder via systemd-resolved
services.fips.gateway.enable	bool	false	Enable the outbound LAN gateway (fips-gateway.service)

What it does

• Installs the fips, fipsctl, fipstop, and fips-gateway binaries
• Creates a fips group (add your user for non-sudo fipsctl/fipstop)
• Seeds /var/lib/fips/fips.yaml and /etc/fips/hosts from the shipped defaults on first run only — operator edits are never clobbered
• Runs fips as a systemd service (fips.service) as root:fips (root is required for TUN interfaces and raw sockets)
• Routes .fips DNS queries to the fips responder on [::1]:5354 via systemd-resolved (enabled by default; disable with services.fips.dns.enable = false)
• Optionally runs the outbound LAN gateway (fips-gateway.service)
• Opens firewall ports for UDP (2121) and TCP (8443) transports

Config file layout (hybrid pattern)

FIPS uses a hybrid config pattern that balances declarative defaults with operator-editable runtime state:

Path	Purpose	Writable	Seeded from
/var/lib/fips/fips.yaml	Main config	yes	services.fips.configFile (first run only)
/var/lib/fips/fips.key	Node identity (private)	yes	generated by fips on first start with persistent: true
/var/lib/fips/fips.pub	Node identity (public)	yes	written by fips on every start
/etc/fips/hosts	Static hostname → npub map	yes	shipped hosts (first run only)
/etc/fips/peers.allow	Peer allowlist (ACL)	yes	operator-created
/etc/fips/peers.deny	Peer denylist (ACL)	yes	operator-created
/etc/fips/fips.d/	nftables drop-in rules	yes	operator-created

Why two locations?

• /var/lib/fips/ holds the main config and identity keys. This survives system rebuilds and reboots. fips derives key paths from the config file's parent directory, so fips.key/fips.pub land here automatically.
• /etc/fips/ holds the hosts file and ACL files. fips hardcodes these paths on Linux (DEFAULT_HOSTS_PATH, DEFAULT_PEERS_ALLOW_PATH, DEFAULT_PEERS_DENY_PATH), so they cannot be relocated.

Why not environment.etc?

NixOS environment.etc creates symlinks into the read-only Nix store. That makes files immutable at runtime and would clobber operator edits on every rebuild. The module instead seeds real writable files via a preStart script that only runs when the target file is absent.

Why --config /var/lib/fips/fips.yaml?

fips has a config search path (./fips.yaml, ~/.fips.yaml, ~/.config/fips/fips.yaml, /etc/fips/fips.yaml). Passing --config explicitly bypasses that search path entirely, so fips loads only the user-managed file and never accidentally picks up a stale /etc/fips/fips.yaml.

Usage after install

sudo journalctl -u fips -f     # follow logs
fipsctl show status            # check status (needs fips group membership)
fipstop                        # live monitoring

To use fipsctl/fipstop without sudo, add your user to the fips group:

users.users.myuser.extraGroups = [ "fips" ];

Log out and back in for the group change to take effect.

Editing config at runtime

sudo nano /var/lib/fips/fips.yaml   # edit main config
sudo nano /etc/fips/hosts           # add static hostname mappings
sudo nano /etc/fips/peers.allow     # add peers to the allowlist
sudo systemctl restart fips         # apply changes

Files are group-writable (0664, owned by root:fips), so fips group members can edit without sudo.

Files

packaging/nixos/
├── default.nix   # NixOS module (services.fips.*)
└── README.md     # this file

The flake also exposes:

• overlays.default — adds pkgs.fips
• nixosModules.default — the NixOS module