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Endlessly downloading nothingness....

OutThere

OutThere

macrumors 603
Original poster
Dec 19, 2002
5,730
3
NYC
I have no idea what is going on with my computer. It is constantly downloading something, from somewhere, apparently without saving it to the hard drive or anything (no HD activity), with no applications open.

It seems to be running pretty much at the max speed of my internet (college internet speed varies depending on the time of day), so it can be anywhere from 300 KB/s to more than 1 MB/s (my computer hates that).

It comes back after restarting, though I haven't observed it closely enough to see exactly how/when it comes back. It's there whether or not I have apps open. It seems to be generating anywhere from 10-30% processor use as well, depending on how fast it's going.

Gahhhhhhhhhhhhhh! :rolleyes:
 

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Yes I am on a college network, but I have all of my file sharing services off, and it keeps up even with iTunes closed. It also continues on the college's wireless network, making it so that I have absurdly little battery life.

Also, little snitch reports nothing on 'Deny All', and even with ethernet and airport off/unplugged it continues to download at 8KB/s (I don't know how that works).
 
i have that same problem, except that i am uploading stuff as well. i am also on a college network. But they have the internet here locked down so tight its not even funny so i don't think its some computer out there. I've looked under windows and it is not downloading anything. Here's a pic.

 
A couple places you can look to see what is going on with the network:

In Network Utility, you can use Netstat. (the netstat command is also available from the terminal, try netstat -f inet to trim the output to the generally interesting parts)

Also from terminal, lsof -i can give an interesting view of what is connecting where. Prefix that with sudo (password prompt will follow) to see everything, not just your own processes.
 
Did you upgrade to the latest iTunes. It could be cover art downloads.

I suggest you download Little Snitch. It monitors all communication from your computer and will tell you whats talking to what.
 
Thanks for the advice, especially the terminal advice iMeowbot.

I have updated iTunes to v7, but it already went through its album art process, and the downloading continues regardless of iTunes being open or closed.

As to Little Snitch, I turned it on (demo mode which is supposed to be fully functional), set it to Deny All and it didn't report any attempts at network connections.

I've attached my netstat results, which seem to show activity under the processes "*.mdns", which seem to be receiving something constantly. I tried force-quitting the mDNSResponder process in the terminal (which, incidentally uses a significant amount of processor), which caused the network activity to spike suddenly and then drop off to 0 for just a moment before the process came back. I'm pretty sure that that's the problem...but what is it doing, and how do I fix it?
 

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I was going to ask you about any FTP or bittorrent apps but you already stated they are closed...its got to be something on that network...have you try taking your laptop to a cafe and see if you get that same spike?


Bless
 
mDNS is multicast DNS and is the source of Bonjour/Rendezvous activity.
It's poling for printers, computers, and other devices.

As iMeowbot said, you should try using lsof to find the culprit.
 
Just a hunch: turn off the sharing stuff in iTunes to see what happens. In a campus environment, there are going to be people looking for shared playlists constantly.
 
Folding wouldn't have anything to do with it owuld it?

I have noticed a couple of times that the computer that i have running folding@home on, would take a while to download some files sometimes. I have it running on an AMD 64 bit computer.

Just a guess.
 
it doesn't have anything to do with itunes because i showed i had the same problem but my itunes isn't open. Neither do i have bit torrent open, or any internet application.

Now that i think about this i had this problem on my g4 like a year ago(home network), never could figure out what it was and eventually i just gave up.
 
I think I can definitely rule out iTunes/file sharing as it continues just as much with iTunes closed, and with iTunes open with sharing both on and off, and with my file sharing protocols on and off, plus I don't have folding@home.

I ran lsof and netstat at the same time, with no apps open other than activity monitor and the terminal, but I'm not sure how to interpret the results (attached). Note the disproportion between the upload and download/packets in/out totals in the activity monitor.

If it means anything, with ethernet on DHCP IPv4 it runs full blast, when IPv4 is off, and only IPv6 is on it runs at like 10-15 kB/s and with IPv6 and IPv4 are both off, it stops altogether.
 

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Makes me wonder if it's registering the connections to localhost as upload/download. How to check?

Pull your network connection. Still getting up/down traffic? Then it's localhost.

EDIT: Just testing it..

Turned off all my network connections and I was still getting data received traffic, which means it's localhost traffic.

99.9999% likely this is what you're seeing.
 
yellow said:
Makes me wonder if it's registering the connections to localhost as upload/download. How to check?

Pull your network connection. Still getting up/down traffic? Then it's localhost.

EDIT: Just testing it..

Turned off all my network connections and I was still getting data received traffic, which means it's localhost traffic.

99.9999% likely this is what you're seeing.
Click to expand...

damn. you had me excited....until I pulled my ethernet. doh! :cool:

If pictures tell 1000 words, you should be able to see right where I pulled the ethernet:

edit: the behavior is repeatable...it flatlines for as long as the ethernet is out, and I also repaired permissions (again) in the mean time.
 

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Odd.. guess I hit the .0001% wall there. :)

Well you can always install ethereal with fink and sniff all the network traffic for a bit.

Frankly, I don't see anything in the the lsof or netstat output that would alarm me too much.
 
yellow said:
Odd.. guess I hit the .0001% wall there. :)

Well you can always install ethereal with fink and sniff all the network traffic for a bit.
Click to expand...

Done...but after my fantasy hockey draft. :D
 
Ok. So I installed ethereal (awesome app btw), sniffed packets for a little bit and then let it analyze what had come and gone...so apparently it's entirely MDNS "Standard Query" and then "Standard Query Response" from other people's shared iTunes on the network, and computer names ending in .local, regardless of whether I have iTunes open or any sort of sharing open.

Each query and response is a few hundred bytes, and thousands upon thousands go through every second, so that's where the bandwidth comes in, by why in the hell is my computer being wtfpwned by all the other macs/iTunes on my network!?

I'm close to just blocking port 5353 (mdns) from all traffic. Maybe that would do the trick?
 
Just know if you do that, you can't use Bonjour to find devices/shares on your network.

What if you explicitly turn off iTunes sharing in iTunes? Are you sure it's not Bonjour enabled iChat query/responses that are also being added, or what it clearly iTunes related in the packets?
 
yellow said:
Just know if you do that, you can't use Bonjour to find devices/shares on your network.

What if you explicitly turn off iTunes sharing in iTunes? Are you sure it's not Bonjour enabled iChat query/responses that are also being added, or what it clearly iTunes related in the packets?
Click to expand...

Well it appears that renaming the /usr/sbin/mDNSResponder to mDNSResponder.bak and force quitting it from the activity monitor solved the problem. Granted I have no bonjour services right now, but my processor does idle at 0% instead of 30%, and I can video chat properly without weird choppy lag.

I guess I'll find out quickly what apps rely on bonjour (I've heard there are some), and bonjour will have to wait until my next system reinstall.

There does still seem to be an 8-10k/s trickle coming in but I don't know where it's coming from and when I launch ethereal something starts generating mDNS queries again....so I can't isolate what exactly is causing the continued data, but I honestly couldn't care less, as my computer actually works right now.

In conclusion: my computer hates me. :p

edit: it seems that more computers than just mine are doing this. I just checked my roomies ibook and, lo and behold, it's cranking away at 400k, as are a couple other macs around.

The question there is: where's the bug? Maybe I should talk to IT.
 
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