MDNS

AndySocial · 07-20-2011, 08:53 PM

Should I be concerned that, ever since updating to 0.8.10, Calibre is permanently connected to 224.0.0.251, downloading at 400kbps all day and night? From what I can tell, that IP address doesn't route to the public internet, but what in the world is it DOING?

kovidgoyal · 07-20-2011, 11:26 PM

That IP address is used for MDNS. As best as I can tell (and I'm no MDNS expert) you've got something on your system broadcasting on it continuously, calibre is presumably reading those broadcasts.

AndySocial · 07-21-2011, 07:42 AM

But it's only Calibre connecting to it, and the previous version didn't. Nothing else on my system changed between the 8.9 and 8.10 updates, so what is Calibre looking for in the MDNS broadcast which I don't even know how to set up and certainly didn't do on purpose? :-)

PeterT · 07-21-2011, 09:05 AM

It's just a local name resolution service being used. I would not loose sleep over it at all!

theducks · 07-21-2011, 09:17 AM

Quote:

Originally Posted by PeterT

It's just a local name resolution service being used. I would not loose sleep over it at all!

at 400Kbps, 24/7

I would worry.
an occasional bust, no problem

something is mis-behaving and wasting cycles. Lots of cycles.
Calibre may just be a victim of something that was waiting to communicate elsewhere.

PeterT · 07-21-2011, 09:57 AM

Quote:

Originally Posted by theducks

something is mis-behaving and wasting cycles. Lots of cycles.
Calibre may just be a victim of something that was waiting to communicate elsewhere.

Such as iTunes or any service that uses Apple's Bonjour / Rendezvous protocols

theducks · 07-21-2011, 10:36 AM

Quote:

Originally Posted by PeterT

Such as iTunes or any service that uses Apple's Bonjour / Rendezvous protocols

And they said NETBUI was too chatty

for a modern Network.

Starson17 · 07-21-2011, 10:37 AM

Quote:

Originally Posted by PeterT

Such as iTunes or any service that uses Apple's Bonjour / Rendezvous protocols

Exactly. My understanding is that Calibre listens for attempts by Apple devices (and other devices using Apple's Bonjour/mDNS) to find the Calibre library. Bonjour simplifies the steps of connecting between the device and the Calibre library so that the user doesn't have to actually enter the address of the computer running Calibre into his Apple device.

Apple's mDNS multicast address is 224.0.0.251 for IPv4, so, if there's a device out there spitting out stuff on that address, Calibre will listen. I'm pretty sure Calibre has done this for a while.

kovidgoyal · 07-21-2011, 10:53 AM

Well nothing has changed in calibre's mdns code between 0.8.9 and 0.8.10. If you dont believe me, see the source.

The mdns modules:

http://bazaar.launchpad.net/~kovid/c...22fmv9z90v2n-2
http://bazaar.launchpad.net/~kovid/c...22fmv9z90v2n-1

The last change was in May.

DoctorOhh · 07-21-2011, 11:12 AM

Quote:

Originally Posted by Starson17

Exactly. My understanding is that Calibre listens for attempts by Apple devices (and other devices using Apple's Bonjour/mDNS) to find the Calibre library. Bonjour simplifies the steps of connecting between the device and the Calibre library so that the user doesn't have to actually enter the address of the computer running Calibre into his Apple device.

Is it possible his neighbor setup a new wireless machine that is chatting with his box?

AndySocial · 07-21-2011, 12:13 PM

When I get home today, I'll see if Bonjour has restarted itself (considering I don't use iTunes and don't have anything except basic QT installed, that service is HARD TO KILL). If that resolves it, I shall post.

I'm not too concerned with the bandwidth, as I can watch my router and see that the 400kbps it's drawing is internal to the local network, not hitting the internet at all (as mdns is non-routable). The wasted cycles are a minor thing, but more it just is one of those things that are behaving in a way I don't understand.

Kovid - I'm not going to EVER try to sharpshoot your source code. :-)

AndySocial · 07-21-2011, 04:14 PM

Now poking into the system again... Bonjour is not running, and nothing else that seems to be an obvious mDNS source is either. I even killed off the UPnP stuff in Windows Services, and the connection persists. Other than shutting down the Calibre program entirely, the only way I can make the connection stop is by shutting down the Calibre server (which I use infrequently, but like to know it's there anyway).

Eh. Not a huge deal, just a strange little curiosity.

kovidgoyal · 07-21-2011, 04:34 PM

Use wireshark or whatever the equivalent is on OSX to get more info on the packets.

AndySocial · 07-21-2011, 07:45 PM

Using Wireshark (ooh, new toy!) it immediately became apparent that my Canon Pixma printer was broadcasting an mDNS heartbeat. I restarted the printer, and it stopped doing that. Weird. It didn't shed any light on why it only wanted to talk to Calibre, but maybe nothing else on my simple system is open to the shameless promiscuity of the mDNS broadcasts.

Thanks for helping me pinpoint the odd stuff. Oh, and Calibre rocks!

Starson17 · 07-22-2011, 10:13 AM

Quote:

Originally Posted by AndySocial

my Canon Pixma printer was broadcasting an mDNS heartbeat.

Thanks for posting to let us know the answer to the mystery.

07-20-2011, 08:53 PM	#1
AndySocial Member Posts: 16 Karma: 101 Join Date: Jul 2011 Device: Kindle, Aluratek Libre Pro	MDNS Should I be concerned that, ever since updating to 0.8.10, Calibre is permanently connected to 224.0.0.251, downloading at 400kbps all day and night? From what I can tell, that IP address doesn't route to the public internet, but what in the world is it DOING?

07-21-2011, 10:53 AM	#9
kovidgoyal creator of calibre Posts: 45,345 Karma: 27182818 Join Date: Oct 2006 Location: Mumbai, India Device: Various	Well nothing has changed in calibre's mdns code between 0.8.9 and 0.8.10. If you dont believe me, see the source. The mdns modules: http://bazaar.launchpad.net/~kovid/c...22fmv9z90v2n-2 http://bazaar.launchpad.net/~kovid/c...22fmv9z90v2n-1 The last change was in May. Last edited by kovidgoyal; 07-21-2011 at 11:16 AM.

07-20-2011, 11:26 PM	#2
kovidgoyal creator of calibre Posts: 45,345 Karma: 27182818 Join Date: Oct 2006 Location: Mumbai, India Device: Various	That IP address is used for MDNS. As best as I can tell (and I'm no MDNS expert) you've got something on your system broadcasting on it continuously, calibre is presumably reading those broadcasts.

07-21-2011, 07:42 AM	#3
AndySocial Member Posts: 16 Karma: 101 Join Date: Jul 2011 Device: Kindle, Aluratek Libre Pro	But it's only Calibre connecting to it, and the previous version didn't. Nothing else on my system changed between the 8.9 and 8.10 updates, so what is Calibre looking for in the MDNS broadcast which I don't even know how to set up and certainly didn't do on purpose? :-)

07-21-2011, 09:05 AM	#4
PeterT Grand Sorcerer Posts: 13,507 Karma: 78910112 Join Date: Nov 2007 Location: Toronto Device: Libra H2O, Libra Colour	It's just a local name resolution service being used. I would not loose sleep over it at all!

07-21-2011, 12:13 PM	#11
AndySocial Member Posts: 16 Karma: 101 Join Date: Jul 2011 Device: Kindle, Aluratek Libre Pro	When I get home today, I'll see if Bonjour has restarted itself (considering I don't use iTunes and don't have anything except basic QT installed, that service is HARD TO KILL). If that resolves it, I shall post. I'm not too concerned with the bandwidth, as I can watch my router and see that the 400kbps it's drawing is internal to the local network, not hitting the internet at all (as mdns is non-routable). The wasted cycles are a minor thing, but more it just is one of those things that are behaving in a way I don't understand. Kovid - I'm not going to EVER try to sharpshoot your source code. :-)

07-21-2011, 04:14 PM	#12
AndySocial Member Posts: 16 Karma: 101 Join Date: Jul 2011 Device: Kindle, Aluratek Libre Pro	Now poking into the system again... Bonjour is not running, and nothing else that seems to be an obvious mDNS source is either. I even killed off the UPnP stuff in Windows Services, and the connection persists. Other than shutting down the Calibre program entirely, the only way I can make the connection stop is by shutting down the Calibre server (which I use infrequently, but like to know it's there anyway). Eh. Not a huge deal, just a strange little curiosity.

07-21-2011, 04:34 PM	#13
kovidgoyal creator of calibre Posts: 45,345 Karma: 27182818 Join Date: Oct 2006 Location: Mumbai, India Device: Various	Use wireshark or whatever the equivalent is on OSX to get more info on the packets.

07-21-2011, 07:45 PM	#14
AndySocial Member Posts: 16 Karma: 101 Join Date: Jul 2011 Device: Kindle, Aluratek Libre Pro	Using Wireshark (ooh, new toy!) it immediately became apparent that my Canon Pixma printer was broadcasting an mDNS heartbeat. I restarted the printer, and it stopped doing that. Weird. It didn't shed any light on why it only wanted to talk to Calibre, but maybe nothing else on my simple system is open to the shameless promiscuity of the mDNS broadcasts. Thanks for helping me pinpoint the odd stuff. Oh, and Calibre rocks!

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