Bug#813754: [Pkg-mpd-maintainers] Bug#813754: Bug#813754: Can't open port 6600 when run syste, -wide vis systemd

[Matthew E. J. Draisey]

I just fixed a situation where I couldn't get mpd to work over my home network.
I think it may be this same issue.

On my system

# sysctl net/ipv6/bindv6only
net.ipv6.bindv6only = 1

netstat would show init listening on [::]:6600 but doesn't report the
IPV6_V6ONLY socket state so I had missed there was no socket listening on ipv4.

Adding

[Socket]
BindIPv6Only=both

to the mpd.socket unit fixed my problem.





On Mon, 12 Sep 2016 22:50:00 +0200 Florian Schlichting  wrote:
> Control: tags 813754 +moreinfo
> > Correct.
> > 
> > > so port 6600 should be open and you
> > > should see systemd listening there until the first connection is
> > > actually made.
> > > 
> > > What is the netstat output after system startup?
> > 
> > # netstat -putan | grep mpd
> > tcp0  0 0.0.0.0:80000.0.0.0:*   LISTEN  
> > 721/mpd
> > 
> > Nos I never though of grepping 6600:
> >  
> > # netstat -putan | grep 6600
> > tcp6   0  0 :::6600 :::*LISTEN  
> > 1/init

Bug#813754: [Pkg-mpd-maintainers] Bug#813754: Bug#813754: Can't open port 6600 when run syste, -wide vis systemd

[Lisandro Damián Nicanor Pérez Meyer]

On martes, 13 de septiembre de 2016 12:45:17 A. M. ART Florian Schlichting 
wrote:
> On Mon, Sep 12, 2016 at 06:36:00PM -0300, Lisandro Damián Nicanor Pérez 
Meyer wrote:
> > I expect that, if the daemon is not running and a client tries to connect
> > to port 6600 then systemd will start the daemon and the client wouldn't
> > even notice it.
> 
> yes, and that works for me.

Not for me I'm afraid ;-)

[snip]

I'll happily test this once my machine is back online, as I recently moved. 
I'm afraid testing this will probably take me more than a week.
 
> I can't imagine why that may be. Are you sure you're running with the same
> mpd config in both cases, and it's not just an artefact of systemd starting
> an mpd with an empty music database?

I've just configured /etc/mpd.conf. As I wrote above, I'll happily re test 
once the machine is up.


-- 
Wiki is not WysiWyg. It's an intelligence test of sorts to be able to edit a
wiki page. It's not rocket science, but it doesn't appeal to the VideoAddicts.
If it doesn't appeal, they don't participate, which leaves those of us who
read and write to get on with rational discourse.
  http://www.c2.com/cgi/wiki?WhyWikiWorks

Lisandro Damián Nicanor Pérez Meyer
http://perezmeyer.com.ar/
http://perezmeyer.blogspot.com/


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Bug#813754: [Pkg-mpd-maintainers] Bug#813754: Bug#813754: Can't open port 6600 when run syste, -wide vis systemd

[Florian Schlichting]

On Mon, Sep 12, 2016 at 06:36:00PM -0300, Lisandro Damián Nicanor Pérez Meyer 
wrote:
> I expect that, if the daemon is not running and a client tries to connect to 
> port 6600 then systemd will start the daemon and the client wouldn't even 
> notice it.

yes, and that works for me.


1) There is no mpd running, mpd.service is inactive, while mpd.socket is
active and PID 1/systemd is listening on port 6600:

[fs@tp] 1 (~): pgrep mpd
(empty)

[fs@tp] 2 (~): systemctl status mpd.service
 mpd.service - Music Player Daemon
   Loaded: loaded (/lib/systemd/system/mpd.service; disabled; vendor preset: 
enabled)
   Active: inactive (dead) since Di 2016-09-13 00:10:44 CEST; 9s ago
[...]

[fs@tp] 3 (~): systemctl status mpd.socket
 mpd.socket
   Loaded: loaded (/lib/systemd/system/mpd.socket; disabled; vendor preset: 
enabled)
   Active: active (listening) since Di 2016-09-13 00:09:40 CEST; 1min 23s ago
   Listen: /run/mpd/socket (Stream)
   [::]:6600 (Stream)

[fs@tp] 4 (~): sudo netstat -lntp | grep 6600
tcp6   0  0 :::6600 :::*LISTEN  
1/systemd



2) Now if I issue a command to the socket (either through mpc or by
starting up MPDroid), the mpd.service unit is activated, an mpd process
is started, but port 6600 still seems to be owned by systemd:

[fs@tp] 5 (~): mpc -h localhost play
Adele/Adele - Hello.mp3
[playing] #2/3   0:14/6:07 (3%)
volume: n/a   repeat: off   random: off   single: off   consume: off

[fs@tp] 6 (~): systemctl status mpd.service
 mpd.service - Music Player Daemon
   Loaded: loaded (/lib/systemd/system/mpd.service; disabled; vendor preset: 
enabled)
   Active: active (running) since Di 2016-09-13 00:12:48 CEST; 15min ago

[fs@tp] 7 (~): pgrep mpd
25884

[fs@tp] 8 (mpd/mpd): sudo netstat -lntp | grep 6600
tcp6   0  0 :::6600 :::*LISTEN  
1/systemd


> That's not happening.

I can't imagine why that may be. Are you sure you're running with the same mpd
config in both cases, and it's not just an artefact of systemd starting
an mpd with an empty music database?

> > netstat output doesn't show
> > "mpd", but everything still works as one would expect, no?
> 
> No, the client can't reach the server unless I start mpd as described in the 
> bug.

Since netstat shows "something" listening on port 6600, what does 

mpc -h localhost status

show? What do you get when you 'telnet localhost 6600'?

Florian

Bug#813754: [Pkg-mpd-maintainers] Bug#813754: Bug#813754: Can't open port 6600 when run syste, -wide vis systemd

[Lisandro Damián Nicanor Pérez Meyer]

Control: tag -1 - moreinfo

On lunes, 12 de septiembre de 2016 10:50:00 P. M. ART Florian Schlichting 
wrote:
> Hi Lisandro,

Hi!
 
> back in February you reported #813754 against mpd, claiming it would not
> open port 6600 if started via systemd.
> 
> I just re-read our email exchange, and I think you'were just confused
> about how systemd socket activation works. 

I expect that, if the daemon is not running and a client tries to connect to 
port 6600 then systemd will start the daemon and the client wouldn't even 
notice it.

That's not happening.

If I'm still wrong in my expectations about systemd and sockets, please read 
below at least to understand what I see as a bug.

> netstat output doesn't show
> "mpd", but everything still works as one would expect, no?

No, the client can't reach the server unless I start mpd as described in the 
bug.

> Please confirm that #813754 doesn't need to be kept open, or else please
> describe what is not working for you?

I would expect turning on my machine, fire my mpd android client app and enjoy 
music :) But I'm getting a client that can't connect to the server unless I 
start mpd as described in the bug.

-- 
Gabardinas "Windows 95". Se cuelgan solas.

Lisandro Damián Nicanor Pérez Meyer
http://perezmeyer.com.ar/
http://perezmeyer.blogspot.com/


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Bug#813754: [Pkg-mpd-maintainers] Bug#813754: Bug#813754: Can't open port 6600 when run syste, -wide vis systemd

[Florian Schlichting]

Control: tags 813754 +moreinfo


Hi Lisandro,

back in February you reported #813754 against mpd, claiming it would not
open port 6600 if started via systemd.

I just re-read our email exchange, and I think you'were just confused
about how systemd socket activation works. netstat output doesn't show
"mpd", but everything still works as one would expect, no?

Please confirm that #813754 doesn't need to be kept open, or else please
describe what is not working for you?

Florian


On Tue, Feb 09, 2016 at 01:16:15AM -0300, Lisandro Damián Nicanor Pérez Meyer 
wrote:
> On Monday 08 February 2016 21:21:20 you wrote:
> > Hi Lisandro,
> > 
> > > Hi! I use mpd on my personal machine as a system service, without
> > > pulseaudio.
> > > 
> > > I noticed that if I let mpd start via systemd port 6600 will not be
> > > opened.
> > 
> > mpd uses systemd's socket activation feature, as defined in
> > /lib/systemd/system/mpd.socket,
> 
> Correct.
> 
> > so port 6600 should be open and you
> > should see systemd listening there until the first connection is
> > actually made.
> > 
> > What is the netstat output after system startup?
> 
> # netstat -putan | grep mpd
> tcp0  0 0.0.0.0:80000.0.0.0:*   LISTEN
>   721/mpd
> 
> Nos I never though of grepping 6600:
>  
> # netstat -putan | grep 6600
> tcp6   0  0 :::6600 :::*LISTEN
>   1/init