Node exporter: Opening firewall once is enough

nixos/modules/monitoring/exporters/node.nix

@@ -14,8 +14,6 @@ let
   mountsFileSystemType = fsType: {} != filterAttrs (n: v: v.fsType == fsType) config.fileSystems;
 
 in {
-  config.networking.firewall.allowedTCPPorts = [ 9100 ];
-
   config.services.prometheus.exporters.node = {
     enable = true;
     openFirewall = true;