Opened 5 years ago

Last modified 3 years ago

#1335 infoneeded bug

Fon "eating" 3G bandwidth

Reported by: Fiol Owned by:
Priority: normal Milestone:
Component: fon-network-3g Version: (Paco)
Severity: unknown
Cc: Hardware: 2.0n (FON2300)


Hi. My router is connected to the internet using a 3G dongle. Even when "idling" (ie. connected but not doing any surfing), I seem to be using a lot of data (over 100Mb every 24 hours).

I then changed the configuration with the router connected to an Android phone in hotspot mode (using the same SIM) and now the data used in idle mode has dropped to near zero (less than 2Mb / 24 hours).

Do you have any ideas on what can explain this? - I can only think that the Fon pings to keep the 3G connection alive but even so, the data use is excessive.


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Change History (6)

comment:1 Changed 5 years ago by matthijs

  • Status changed from new to infoneeded

That bandwidth usage does seem excessive.

The first thing that comes to mind is the onlined checks (that allow the router to detect if it has a working internet connection or not). These checks happen once every minute and a typical DNS query and response packet is around 80 bytes (I didn't check the actual packets sent by the Fonera, but real values should be similar). In 24 hours, this adds up to a little over 100 kbyte, so I don't think this is it.

Perhaps you can make a packet dump to see what data is being transferred during idle? The easiest way to do this would be to install tcpdump. If you're running a DEV version of the firmware, you could run these commands through SSH. The first command installs the tcpdump command:

root@Fonera:~# opkg install tcpdump

After this, you can dump traffic with this command:

root@Fonera:~# tcpdump -s 0 -w /tmp/dump -i ppp0

This makes a dump of the ppp0 interface, which I think is the interface used by 3G (though it might be ppp1 or another number, you can get a list of all interfaces with the "ifconfig" command.

You should probably leave this running for a quarter of an hour or so, then terminate the dump with control-C. Afterwards, you'll have a file called /tmp/dump containing the dumped packets.

See also reportbugs for more information on running commands through SSH and getting at the resulting data.

You can open the dump file using wireshark ( to see what packets it contains. Alternatively, just send the file over to me (matthijskooijman@…) and I'll have a look (better not attach it to the ticket, in case it contains some actual data).

comment:2 Changed 5 years ago by Fiol

Thanks for you swift response.
Sorry, I am a bit of a noob regarding SSH, Telnet and the like, so need a little more help:
How do I run the ipconfig command?

root@Fonera:~# ipconfig     ?

Am I correct this is the terminate command:

root@Fonera:~# tcpdump -c


comment:3 follow-up: Changed 5 years ago by matthijs

No problem, I'll clarify :-)

There is no ipconfig command on Linux, it's called ifconfig (so with an f).

Terminating the tcpdump is done by pressing control-C, e.g., press and hold the ctrl button on your keyboard, press the "C" button and release both.

Does that help?

comment:4 in reply to: ↑ 3 Changed 5 years ago by Fiol

Hi Matthijs

I get this error:
root@Fonera:~# opkg install tcpdump
An error ocurred, return value: 716563936.

That stumped me[[BR]]
Actually, for your info. I am now using Dev.

comment:5 Changed 5 years ago by matthijs

Oh! I forgot on command:

root@Fonera:~# opkg update

Please run that before the opkg install tcpdump. It updates the list of available packages before you can install them.

comment:6 Changed 3 years ago by anonymous

root@Fonera:~# opkg update

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