add aspects/hosts/ configurations

Host-specific NixOS configurations for:
- alexandria (server)
- io (desktop)
- rotterdam (desktop)
- trantor (server, aarch64)

Each host has a main config file and _hostname/ directory
with hardware-configuration and other host-specific modules.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

aspects/hosts/_trantor/boot.nix

@@ -0,0 +1,6 @@
+{
+  boot = {
+    initrd.systemd.enable = true;
+    loader.efi.efiSysMountPoint = "/boot/efi";
+  };
+}

aspects/hosts/_trantor/disko.nix

@@ -0,0 +1,64 @@
+{ inputs, ... }:
+
+{
+  imports = [ inputs.disko.nixosModules.default ];
+
+  disko.devices.disk.main = {
+    type = "disk";
+    device = "/dev/disk/by-id/scsi-360b207ed25d84372a95d1ecf842f8e20";
+    content = {
+      type = "gpt";
+      partitions = {
+        ESP = {
+          priority = 1;
+          name = "ESP";
+          start = "1MiB";
+          end = "512MiB";
+          type = "EF00";
+          content = {
+            type = "filesystem";
+            format = "vfat";
+            mountpoint = "/boot/efi";
+            mountOptions = [
+              "noatime"
+              "fmask=0077"
+              "dmask=0077"
+            ];
+          };
+        };
+        root = {
+          priority = 2;
+          name = "root";
+          size = "100%";
+          content = {
+            type = "btrfs";
+            extraArgs = [ "-f" ];
+            subvolumes = {
+              "@root" = {
+                mountpoint = "/";
+                mountOptions = [
+                  "noatime"
+                  "compress=zstd"
+                ];
+              };
+              "@nix" = {
+                mountpoint = "/nix";
+                mountOptions = [
+                  "noatime"
+                  "compress=zstd"
+                ];
+              };
+              "@persistent" = {
+                mountpoint = "/persistent";
+                mountOptions = [
+                  "noatime"
+                  "compress=zstd"
+                ];
+              };
+            };
+          };
+        };
+      };
+    };
+  };
+}

aspects/hosts/_trantor/fail2ban.nix

@@ -0,0 +1,23 @@
+{ config, pkgs, ... }:
+
+{
+  services.fail2ban = {
+    enable = true;
+    maxretry = 5;
+    ignoreIP = [
+      "127.0.0.0/8"
+      "::1"
+      "10.0.0.0/8"
+      "172.16.0.0/12"
+      "192.168.0.0/16"
+      "100.64.0.0/10"
+    ];
+    bantime = "1h";
+    bantime-increment = {
+      enable = true;
+      multipliers = "1 2 4 8 16 32 64";
+      maxtime = "10000h";
+      overalljails = true;
+    };
+  };
+}

aspects/hosts/_trantor/forgejo.nix

@@ -0,0 +1,72 @@
+{
+  config,
+  lib,
+  inputs,
+  ...
+}:
+
+let
+  utils = import ../../../utils.nix { inherit inputs lib; };
+  inherit (utils) mkNginxVHosts;
+in
+
+{
+  services = {
+    forgejo = {
+      enable = true;
+      settings = {
+        session.COOKIE_SECURE = true;
+        server = {
+          PROTOCOL = "http+unix";
+          DOMAIN = "git.baduhai.dev";
+          ROOT_URL = "https://git.baduhai.dev";
+          OFFLINE_MODE = true; # disable use of CDNs
+          SSH_DOMAIN = "git.baduhai.dev";
+        };
+        log.LEVEL = "Warn";
+        mailer.ENABLED = false;
+        actions.ENABLED = false;
+        service.DISABLE_REGISTRATION = true;
+        oauth2_client = {
+          ENABLE_AUTO_REGISTRATION = true;
+          UPDATE_AVATAR = true;
+          ACCOUNT_LINKING = "login";
+          USERNAME = "preferred_username";
+        };
+      };
+    };
+    nginx.virtualHosts = mkNginxVHosts {
+      domains."git.baduhai.dev".locations."/".proxyPass =
+        "http://unix:${config.services.forgejo.settings.server.HTTP_ADDR}:/";
+    };
+    fail2ban.jails.forgejo = {
+      settings = {
+        enabled = true;
+        filter = "forgejo";
+        maxretry = 3;
+        findtime = "10m";
+        bantime = "1h";
+      };
+    };
+  };
+
+  environment = {
+    etc."fail2ban/filter.d/forgejo.conf".text = ''
+      [Definition]
+      failregex = .*(Failed authentication attempt|invalid credentials|Attempted access of unknown user).* from <HOST>
+      ignoreregex =
+      journalmatch = _SYSTEMD_UNIT=forgejo.service
+    '';
+
+    persistence.main.directories = [
+      {
+        directory = config.services.forgejo.stateDir;
+        inherit (config.services.forgejo) user group;
+        mode = "0700";
+      }
+    ];
+  };
+
+  # Disable PrivateMounts to allow LoadCredential to work with bind-mounted directories
+  systemd.services.forgejo.serviceConfig.PrivateMounts = lib.mkForce false;
+}

aspects/hosts/_trantor/hardware-configuration.nix

@@ -0,0 +1,20 @@
+{
+  lib,
+  modulesPath,
+  ...
+}:
+
+{
+  imports = [ (modulesPath + "/profiles/qemu-guest.nix") ];
+
+  boot.initrd.availableKernelModules = [
+    "xhci_pci"
+    "virtio_pci"
+    "virtio_scsi"
+    "usbhid"
+  ];
+
+  networking.useDHCP = lib.mkDefault true;
+
+  nixpkgs.hostPlatform = lib.mkDefault "aarch64-linux";
+}

aspects/hosts/_trantor/networking.nix

@@ -0,0 +1,8 @@
+{
+  networking = {
+    firewall = {
+      allowedTCPPorts = [ 25566 ];
+      allowedUDPPorts = [ 25566 ];
+    };
+  };
+}

aspects/hosts/_trantor/nginx.nix

@@ -0,0 +1,61 @@
+{
+  config,
+  lib,
+  inputs,
+  ...
+}:
+
+let
+  utils = import ../../../utils.nix { inherit inputs lib; };
+  inherit (utils) mkNginxVHosts services;
+
+  # Get all unique domains from shared services on trantor (host = "trantor")
+  localDomains = lib.unique (
+    map (s: s.domain) (lib.filter (s: s.host == "trantor") services)
+  );
+
+  # Generate ACME cert configs for all local domains
+  acmeCerts = lib.genAttrs localDomains (domain: {
+    group = "nginx";
+  });
+in
+
+{
+  security.acme = {
+    acceptTerms = true;
+    defaults = {
+      email = "baduhai@proton.me";
+      dnsResolver = "1.1.1.1:53";
+      dnsProvider = "cloudflare";
+      credentialsFile = config.age.secrets.cloudflare.path;
+    };
+    certs = acmeCerts;
+  };
+
+  services.nginx = {
+    enable = true;
+    recommendedGzipSettings = true;
+    recommendedOptimisation = true;
+    recommendedProxySettings = true;
+    recommendedTlsSettings = true;
+    virtualHosts = {
+      "_" = {
+        default = true;
+        locations."/".return = "444";
+      };
+    };
+  };
+
+  users.users.nginx.extraGroups = [ "acme" ];
+
+  networking.firewall.allowedTCPPorts = [
+    80
+    443
+  ];
+
+  age.secrets.cloudflare = {
+    file = ../../../secrets/cloudflare.age;
+    owner = "nginx";
+    group = "nginx";
+  };
+}

aspects/hosts/_trantor/openssh.nix

@@ -0,0 +1,23 @@
+{ ... }:
+
+{
+  services = {
+    openssh = {
+      settings = {
+        PasswordAuthentication = false;
+        KbdInteractiveAuthentication = false;
+      };
+    };
+    fail2ban.jails.sshd = {
+      settings = {
+        enabled = true;
+        port = "ssh";
+        filter = "sshd";
+        logpath = "/var/log/auth.log";
+        maxretry = 3;
+        findtime = "10m";
+        bantime = "1h";
+      };
+    };
+  };
+}

aspects/hosts/_trantor/unbound.nix

@@ -0,0 +1,58 @@
+{ inputs, lib, ... }:
+
+let
+  utils = import ../../../utils.nix { inherit inputs lib; };
+in
+
+{
+  services.unbound = {
+    enable = true;
+    enableRootTrustAnchor = true;
+    settings = {
+      server = {
+        interface = [
+          "0.0.0.0"
+          "::"
+        ];
+        access-control = [
+          "127.0.0.0/8 allow"
+          "100.64.0.0/10 allow" # Tailscale CGNAT range
+          "::1/128 allow"
+          "fd7a:115c:a1e0::/48 allow" # Tailscale IPv6
+        ];
+
+        num-threads = 2;
+        msg-cache-size = "50m";
+        rrset-cache-size = "100m";
+        cache-min-ttl = 300;
+        cache-max-ttl = 86400;
+        prefetch = true;
+        prefetch-key = true;
+        hide-identity = true;
+        hide-version = true;
+        so-rcvbuf = "1m";
+        so-sndbuf = "1m";
+
+        # Tailnet DNS records from shared services
+        local-zone = ''"baduhai.dev." transparent'';
+        local-data = map (e: ''"${e.domain}. IN A ${e.tailscaleIP}"'') utils.services;
+      };
+
+      forward-zone = [
+        {
+          name = ".";
+          forward-addr = [
+            "1.1.1.1@853#cloudflare-dns.com"
+            "1.0.0.1@853#cloudflare-dns.com"
+          ];
+          forward-tls-upstream = true;
+        }
+      ];
+    };
+  };
+
+  networking.firewall = {
+    allowedTCPPorts = [ 53 ];
+    allowedUDPPorts = [ 53 ];
+  };
+}