nixos/services/sshd: disable password and root login

nixos/common.nix

@@ -101,6 +101,19 @@ in
     };
   };
 
+  services = {
+    openssh = {
+      enable = true;
+
+      settings = {
+        ClientAliveInterval = 300;
+        PasswordAuthentication = false;
+        KbdInteractiveAuthentication = false;
+        PermitRootLogin = "no";
+      };
+    };
+  };
+
   virtualisation.podman.enable = true;
 
   zramSwap = {