nftables: Warn about correct firewall setting

services.networking.firewall might have existed during import of this
module in 2016, but it is unknown as of today.

Point to the proper boolean knob to avoid confusion.

Changed files
+1 -1
nixos
modules
services
networking
+1 -1
nixos/modules/services/networking/nftables.nix
···
config = mkIf cfg.enable {
assertions = [{
assertion = config.networking.firewall.enable == false;
-
message = "You can not use nftables with services.networking.firewall.";
+
message = "You can not use nftables and iptables at the same time. networking.firewall.enable must be set to false.";
}];
boot.blacklistedKernelModules = [ "ip_tables" ];
environment.systemPackages = [ pkgs.nftables ];