openssh: kill open and stale connections quicker

config/default.nix

@@ -189,6 +189,7 @@
       # Required for deployment and sops
       enable = true;
       settings = {
+        LoginGraceTime = 30; # throw out unauthenticated connections earlier than the 120 default
         PasswordAuthentication = lib.mkIf (!config.c3d2.k-ot.enable) false;
         PermitRootLogin = lib.mkOverride 900 "prohibit-password";
       };