From a5cc8d86c4d64d546d962d25869801919a7a5a3f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=B6rg=20Thalheim?= <joerg@thalheim.io>
Date: Fri, 12 Apr 2024 18:30:20 +0200
Subject: [PATCH] enable multicast dns for desktop machines

It's quite cool if you can just ping machines by hostname.
---
 nixos/default.nix         | 1 +
 nixos/desktop/default.nix | 1 +
 nixos/mixins/mdns.nix     | 7 +++++++
 3 files changed, 9 insertions(+)
 create mode 100644 nixos/mixins/mdns.nix

diff --git a/nixos/default.nix b/nixos/default.nix
index aaf9820..806a15c 100644
--- a/nixos/default.nix
+++ b/nixos/default.nix
@@ -56,6 +56,7 @@ exposeModules ./. [
   ./mixins/tracing.nix
   ./mixins/trusted-nix-caches.nix
   ./mixins/nix-experimental.nix
+  ./mixins/mdns.nix
   ./roles/github-actions-runner.nix
   ./roles/nix-remote-builder.nix
   ./roles/prometheus
diff --git a/nixos/desktop/default.nix b/nixos/desktop/default.nix
index fd222f4..47ddc2b 100644
--- a/nixos/desktop/default.nix
+++ b/nixos/desktop/default.nix
@@ -1,6 +1,7 @@
 { lib, ... }: {
   imports = [
     ../common
+    ../mixins/mdns.nix
     ./pipewire.nix
   ];
 
diff --git a/nixos/mixins/mdns.nix b/nixos/mixins/mdns.nix
new file mode 100644
index 0000000..af57459
--- /dev/null
+++ b/nixos/mixins/mdns.nix
@@ -0,0 +1,7 @@
+{ lib, ... }: {
+  # Allows to find machines on the local network by name, i.e. useful for printer discovery
+  systemd.network.networks."99-ethernet-default-dhcp".networkConfig.MulticastDNS = lib.mkDefault "yes";
+  systemd.network.networks."99-wireless-client-dhcp".networkConfig.MulticastDNS = lib.mkDefault "yes";
+  networking.firewall.allowedUDPPorts = [ 5353 ]; # Multicast DNS
+}
+