add hedgedoc config

services/openssh.nix

@@ -0,0 +1,19 @@
+{ ... }:
+
+{
+  services = {
+    openssh = {
+      enable = true;
+      settings = {
+        PermitEmptyPasswords = "no";
+        PermitRootLogin = "prohibit-password";
+        PasswordAuthentication = false;
+        KbdInteractiveAuthentication = false;
+      };
+    };
+    sshguard = {
+      enable = true;
+      services = [ "sshd" ];
+    };
+  };
+}