Initial commit

configuration.nix

@@ -0,0 +1,121 @@
+{ ... }:
+
+{
+  imports = [
+    ./hardware-configuration.nix
+    # Add further modules here later, e.g.:
+    ./programs.nix
+    # ./modules/nextcloud.nix
+    # ./modules/wireguard.nix
+    # ./modules/docker.nix
+  ];
+
+  # ============================================================
+  # WORKAROUNDS / FIXES
+  # ============================================================
+
+  # Workaround for https://github.com/NixOS/nix/issues/8502
+  services.logrotate.checkConfig = false;
+
+  # ============================================================
+  # BOOT
+  # ============================================================
+
+  # Clear /tmp on every boot
+  boot.tmp.cleanOnBoot = true;
+
+  # ============================================================
+  # MEMORY
+  # ============================================================
+
+  # zram swap (compressed RAM swap, good for small VPS)
+  zramSwap.enable = true;
+
+  # ============================================================
+  # NETWORKING
+  # ============================================================
+
+  networking = {
+    hostName = "nixos";
+    domain   = "system";
+
+    # Firewall – only explicitly allowed ports are open
+    firewall = {
+      enable = true;
+      allowedTCPPorts = [
+        2405  # SSH
+        # 80    # HTTP  (uncomment when needed)
+        # 443   # HTTPS (uncomment when needed)
+      ];
+    };
+  };
+
+  # ============================================================
+  # TIMEZONE & LOCALISATION
+  # ============================================================
+
+  time.timeZone = "Europe/Berlin";
+  i18n.defaultLocale = "de_DE.UTF-8";
+
+  # ============================================================
+  # SSH
+  # ============================================================
+
+  services.openssh = {
+    enable = true;
+    ports  = [ 2405 ];
+
+    settings = {
+      # Only SSH key authentication, no password login
+      PasswordAuthentication = false;
+      # Root login only allowed via SSH key
+      PermitRootLogin        = "prohibit-password";
+      # Disconnect idle connections after 10 minutes
+      ClientAliveInterval    = 300;
+      ClientAliveCountMax    = 2;
+    };
+  };
+
+  # ============================================================
+  # USERS
+  # ============================================================
+
+  users.users.root = {
+    openssh.authorizedKeys.keys = [
+      "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIAhH+p950yRQHwznrvswAhD9aOMF+UjOFZVJgG0vOv2B"
+    ];
+  };
+
+  # ============================================================
+  # NIX / SYSTEM
+  # ============================================================
+
+  nix.settings = {
+    # Automatically deduplicate the nix store
+    auto-optimise-store = true;
+    # Enable flakes
+    experimental-features = [ "nix-command" "flakes" ];
+  };
+
+  # Automatically delete old generations (older than 14 days)
+  nix.gc = {
+    automatic = true;
+    dates     = "weekly";
+    options   = "--delete-older-than 14d";
+  };
+
+  # Rebuild alias
+  programs.bash.shellAliases = {
+  rebuild = "sudo nixos-rebuild switch --flake /etc/nixos#nixos";
+  };
+  programs.zsh.shellAliases = {
+  rebuild = "sudo nixos-rebuild switch --flake /etc/nixos#nixos";
+  };
+
+  # ============================================================
+  # STATE VERSION – DO NOT CHANGE
+  # Indicates with which NixOS version this system was initialised.
+  # Affects certain default settings.
+  # ============================================================
+  system.stateVersion = "23.11";
+}