openssh-server should broadcast availability via avahi

[Mario Limonciello]

Avahi has support to advertise to a network different running services. Currently openssh doesn't advertise itself dynamically or statically when installed.

It can be done statically by copying the example file from /usr/share/doc/avahi-daemon/examples to /etc/avahi/services or by using the avahi-publish command. avahi-publish could be ran from the SSH init script, or this service file can be installed by the openssh-server package.

This can be done dynamically by patching openssh, but there would have to be a buy in from upstream to do this.

[Bastien (bastien-redhat-bugs)]

Avahi should set the TXT record for the SSH service it exports to include the public key of the SSH server (in a manner compatible with MacOS X, which does the same thing).

[Lennart (lennart-redhat-bugs)]

Uh. This is not the appropriate place to report this.

To do this properly we should patch OpenSSH to do the Avahi registration itself. But I fear the OpenSSH would not be willing to merge such a patch. Right now we do mDNS/DNS-SD publishing of the SSH service by dropping a static service definition file in /etc/avahi. It's just an xml file. Including the SSH server key in that file automatically is not really possible.

I am reassigning this now to ssh, let's see what the ssh maintainers have to say about this.

[Tomas (tomas-redhat-bugs)]

I don't know much about the potential avahi registration code, that means what dependencies it would bring to openssh and so on.

But I am really afraid this code would not be accepted upstream especially if some of the dependencies would be GPL licensed.

[Lennart (lennart-redhat-bugs)]

It would pull in libavahi-client which is LGPL. la-c pulls in D-Bus. Which is GPL & Academic.

Also, that dependency would be completely optional.

I'd expect a refusal however due to more fundamental issues. i.e. mDNS/DNS-SD is this unreliable, untrusted protocol that is used to spam the local network about the existance of a service. Security people tend to stay away from technology like that and normally don't see the usefulness of this.

Yes, i know, I am not selling this very well right now.... Let's hope I am mistaken.

[Fedora (fedora-redhat-bugs)]

This package has changed ownership in the Fedora Package Database. Reassigning to the new owner of this component.

[Bug (bug-redhat-bugs)]

This bug appears to have been reported against 'rawhide' during the Fedora 11 development cycle.
Changing version to '11'.

More information and reason for this action is here:
http://fedoraproject.org/wiki/BugZappers/HouseKeeping

[Mario Limonciello (superm1)]

Here's a related bug in F11: https://bugzilla.redhat.com/show_bug.cgi?id=475996

[Jan (jan-redhat-bugs)]

This bug already has been fixed by static avahi registration.

[Bastien (bastien-redhat-bugs)]

Not sure what you mean by that, but key certainly isn't exported using openssh-5.2p1-28.fc12.x86_64:
$ avahi-browse -ar
= eth0 IPv4 cookie SSH Remote Terminal local
   hostname = [cookie.local]
   address = [192.168.1.140]
   port = [22]
   txt = []

[Jan (jan-redhat-bugs)]

It is exactly the same as MacOS exported.

[Bug (bug-redhat-bugs)]

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[Jan (jan-redhat-bugs)]

This may or may not be a part of the avahi code, but it can't be done in openssh. There are no means to provide it.

[Bug (bug-redhat-bugs)]

Fedora 11 changed to end-of-life (EOL) status on 2010-06-25. Fedora 11 is
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[Bruno Nova (brunonova)]

It would be really nice if openssh-server would publish via Avahi the SSH and SFTP services by default.
Examples of both services are provided in /usr/share/doc/avahi-daemon/examples/.

Publishing the SFTP service would be great because Nautilus (and other file managers, I suppose) lists, in it's Network "folder", all computers that are publishing that service, allowing to easily connect to those computers via SFTP and transfer files, much like Samba (no guest access, though).