- ddns_he.env.bin: Hurricane Electric (he.net) passphrase
- ddns_afraid.env.bin: freedns.afraid.org API key
    - viewable: <https://freedns.afraid.org/dynamic/>
- dovecot_passwd: auth for mail accounts
    - passwd file looks like /etc/passwd
    - generate pw hash with: `nix run nixpkgs.apacheHttpd -c htpasswd -nbB "" "my passwd"`
- wg_ovpns_privkey.bin: wireguard private key for OVPN
    - to generate:
        - wg genkey > wg0.private
        - wg pubkey < wg0.private > wg0.public