modules/avahi: Sync module defaults with upstream #361191

frederictobiasc · 2024-12-02T19:56:17Z

This contribution syncs the module's defaults with upstream (man avahi-daemon.conf) defaults.

Motivation is to reduce the effort for getting a standard mdns configuration.

Additionally, this contribution enables nssmdns by default.

Things done

CC: @fpletz @SuperSandro2000

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SuperSandro2000 · 2024-12-03T15:09:05Z

nixos/modules/services/networking/avahi-daemon.nix

@@ -227,7 +227,7 @@ in

    nssmdns6 = lib.mkOption {
      type = lib.types.bool;
-      default = false;
+      default = true;


Suggested change

default = true;

default = false;

see description

SuperSandro2000 · 2024-12-03T15:13:09Z

nixos/modules/services/networking/avahi-daemon.nix

        description = "Whether to announce the locally used domain name for browsing by other hosts.";
      };
    };

    nssmdns4 = lib.mkOption {
      type = lib.types.bool;
-      default = false;
+      default = true;


This is the only option I have ever enabled on any of my clients. I think all the others are just announcing information into the network you are connecting to for no good reason and especially on public wifi we don't want to announce cpu information or why would we?

especially on public wifi we don't want to announce cpu information or why would we?

I agree that probably nobody cares about CPU information on a public Wi-Fi. However, I don't see where this does any harm.

Tracking, mostly. Fingerprinting can involve basically any details of your system, so exposing as little of that as possible is valuable.

What is the use case to publish those information? Why should it be enabled by default if we don't know why we enabled it?

Also do we really want to expand the output of avahi-browse -a with services and information that we coulnd't come up with a reason?

We probably want to change nssmdns4 to default to yes because that is the most common usecase for avahi and without it, it doesn't do much but I cannot follow why we should change all the other options.

SuperSandro2000 · 2024-12-03T15:13:30Z

nixos/modules/services/networking/avahi-daemon.nix

@@ -175,25 +175,25 @@ in
    publish = {
      enable = lib.mkOption {
        type = lib.types.bool;
-        default = false;
+        default = true;


and this I only ever enabled on machines like audio or print servers.

frederictobiasc · 2024-12-03T18:42:03Z

This change reduces setup friction for most users that simply expect a working default avahi configuration when setting services.avahi.enable = true.

For most modules, NixOS users only need to activate the corresponding enable option and can expect a reasonable and working default configuration. This is currently not the case with the avahi module. The avahi module in it's current state deviates significantly from avahi's defaults. I'm convinced that this doesn't align with user's expectations set by the behaviour of other distributions.

@SuperSandro2000 Please keep in mind, this PR does not suggest enabling avahi by default. Users that want to use avahi and have concerns can still review the default configuration - as they would do on any other distribution.

SuperSandro2000 · 2024-12-12T14:50:24Z

For most modules, NixOS users only need to activate the corresponding enable option and can expect a reasonable and working default configuration.

That is not really true. For example many webservices require you to set a domain and sometimes even outright refuse to evaluate if that is not given.

Users that want to use avahi and have concerns can still review the default configuration - as they would do on any other distribution.

The default configuration shouldn't be like: you are almost certainly required to turn this off, to have a good and reasonable experience just because upstream has this or that default. We don't need to copy the bad parts of other distros where you first need to change all the defaults because they suck and are known to be bad defaults.

SuperSandro2000 · 2024-12-12T14:56:43Z

nixos/modules/services/networking/avahi-daemon.nix

        description = "Whether to publish user services. Will set `addresses=true`.";
      };

      addresses = lib.mkOption {
        type = lib.types.bool;
-        default = false;
+        default = true;
        description = "Whether to register mDNS address records for all local IP addresses.";
      };

      hinfo = lib.mkOption {


This is by default no https://github.com/avahi/avahi/blob/1dade81cbf4d3e3f49784e44e543cd77046c79df/man/avahi-daemon.conf.5.xml.in#L252-L259

You're correct. I compared with https://linux.die.net/man/5/avahi-daemon.conf, but the rendered manual targets an older avahi version.

Updated it accordingly.

SuperSandro2000 · 2024-12-12T14:56:56Z

nixos/modules/services/networking/avahi-daemon.nix

      workstation = lib.mkOption {
        type = lib.types.bool;
-        default = false;
+        default = true;
        description = ''
          Whether to register a service of type "_workstation._tcp" on the local LAN.
        '';


same here https://github.com/avahi/avahi/blob/1dade81cbf4d3e3f49784e44e543cd77046c79df/man/avahi-daemon.conf.5.xml.in#L263-L269

As with hinfo, I updated it. Thanks for pointing it out.

SuperSandro2000 · 2024-12-12T14:58:29Z

nixos/modules/services/networking/avahi-daemon.nix

        description = "Whether to allow publishing in general.";
      };

      userServices = lib.mkOption {
        type = lib.types.bool;
-        default = false;
+        default = true;
        description = "Whether to publish user services. Will set `addresses=true`.";
      };

      addresses = lib.mkOption {


This reads like it should only be enabled on publishing servers https://github.com/avahi/avahi/blob/1dade81cbf4d3e3f49784e44e543cd77046c79df/man/avahi-daemon.conf.5.xml.in#L243-L248

No, this is also required to reply to mDNS requests.

SuperSandro2000 · 2024-12-12T14:58:59Z

nixos/modules/services/networking/avahi-daemon.nix

      userServices = lib.mkOption {
        type = lib.types.bool;
-        default = false;
+        default = true;
        description = "Whether to publish user services. Will set `addresses=true`.";
      };


this reads like it is security relevant https://github.com/avahi/avahi/blob/1dade81cbf4d3e3f49784e44e543cd77046c79df/man/avahi-daemon.conf.5.xml.in#L226-L230

There are no default user services. Check extraServiceFiles.

This contribution syncs the module's default with upstream avahi's defaults.

github-actions bot added 6.topic: nixos Issues or PRs affecting NixOS modules, or package usability issues specific to NixOS 8.has: documentation This PR adds or changes documentation 8.has: changelog 8.has: module (update) This PR changes an existing module in `nixos/` labels Dec 2, 2024

frederictobiasc mentioned this pull request Dec 2, 2024

modules/avahi: Enable IPv6 by default #361016

Merged

13 tasks

github-actions bot added 10.rebuild-darwin: 0 This PR does not cause any packages to rebuild on Darwin 10.rebuild-linux: 1-10 labels Dec 2, 2024

SuperSandro2000 reviewed Dec 3, 2024

View reviewed changes

frederictobiasc force-pushed the avahi-defaults branch from 171007b to b37470f Compare December 3, 2024 18:46

SuperSandro2000 reviewed Dec 12, 2024

View reviewed changes

wegank added the 2.status: merge conflict This PR has merge conflicts with the target branch label Dec 31, 2024

frederictobiasc force-pushed the avahi-defaults branch from b37470f to 25a5efb Compare January 13, 2025 10:13

ofborg bot removed the 2.status: merge conflict This PR has merge conflicts with the target branch label Jan 13, 2025

modules/avahi: Sync module defaults with upstream

12c3e67

This contribution syncs the module's default with upstream avahi's defaults.

frederictobiasc force-pushed the avahi-defaults branch from 25a5efb to 12c3e67 Compare January 13, 2025 10:53

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modules/avahi: Sync module defaults with upstream #361191

modules/avahi: Sync module defaults with upstream #361191

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modules/avahi: Sync module defaults with upstream #361191

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