diff --git a/machines/vpn/configuration.nix b/machines/vpn/configuration.nix
index f47d31a7..57e6341b 100644
--- a/machines/vpn/configuration.nix
+++ b/machines/vpn/configuration.nix
@@ -10,6 +10,9 @@ with lib;
     hostName = mkDefault "vpn";
     useDHCP = false;
     nameservers = [ "1.1.1.1" ];
+    firewall = {
+      allowedUDPPorts = [ 51821 ];
+    };
   };
 
   imports = [