Add sshd module

flake.nix

@@ -27,6 +27,7 @@
         nix-gc = import ./modules/nix-gc.nix;
         futureware = import ./modules/futureware.nix;
         tools = import ./modules/tools.nix;
+        sshd = import ./modules/sshd.nix;
       };
 
       lib.pre-commit = import ./pre-commit.nix;

modules/sshd.nix

@@ -0,0 +1,16 @@
+_: {
+  services.openssh = {
+    enable = true;
+    settings.PasswordAuthentication = false;
+    settings.KbdInteractiveAuthentication = false;
+    hostKeys = [
+      # Generate a key if it's missing, which is normal at first boot, but can
+      # also be a TPM failure for PCs with a TPM.
+      # Do not generate an RSA key.
+      {
+        path = "/etc/ssh/ssh_host_ed25519_key";
+        type = "ed25519";
+      }
+    ];
+  };
+}