[systemd-devel] dbus-broker can be used for a "user" type bus accessible over tcp or not?

[Mantas Mikulėnas]

On Tue, Jan 21, 2025 at 8:47 AM Erik Slagter <erik at slagter.name> wrote:

> Hi Lennart,
>
> That is exactly the answer I expected, if only because apparently
> systemd does it exactly that ;-)
>
> But not everything needs to be enterprise-grade. This is going to run
> inside my own house in a piece of network that's completely trusted. I
> can completely imagine it's not sane to do this with the system or even
> session bus, but this is a very simple "request value x for me"
> mechanism, on it's own bus.
>
> It's now running on SUN RPC (with just as little security), but I fear
> that one has had it's longest time, being around for > 30 years and I am
> getting the feeling support is fading. It's also not great to develop
> for. I had a quick look at SOAP but support in C++ seems to be next to
> non-existing and needs a web server. Latest hot stuff seems to be gRPC
> but it's overly complicated and bloated. So I'd like to with DBus which
> happily does what I need.
>

Well, at least SunRPC can have Kerberos authentication available for it
(RPCSEC_GSS). In theory, if I recall correctly, D-Bus uses the SASL
framework and could be made to use GSSAPI or SCRAM (or maybe even TLS with
client certificates), but no current implementation supports any of that;
all are designed to be local-only.

...Though on the other hand, didn't Microsoft once ship a network
D-Bus-based IoT system as part of Windows? I believe that's what "AllJoyn"
was.

I'm not sure if SOAP inherently requires a "web server"? It requires an
HTTP server, yes, but that doesn't necessarily mean a whole Apache2 or IIS.
Accepting HTTP requests is not fundamentally much different from e.g. a
D-Bus server (except with more overhead; I'd prefer JSON-RPC over SOAP, but
anything HTTP-based is definitely not light in itself).

(For my hobby projects I started with JSON-RPC over HTTPS, and ended up
with JSON-RPC inside Kerberos over raw TCP – but both were almost equally
self-contained "RPC servers", in that both kinds of requests were served
in-process and not through any 'web' stack.)

-- 
Mantas Mikulėnas
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