I am using Ubuntu 11.10. I use Mozilla 17.0.1 as my browser.

I have been noticing this incident for the past few days.
Even when my browser is not downloading anything or if I have closed the Mozilla browser, the system monitor shows bytes being received.
I checked the update manager: It shows that "package information was updated 2 hours ago" etc. So I assume that it is not the update manager which is trying to download something.

My question is

1)is it because of some virus? I have the UFW up and running. I haven't installed any other anti virus. Is it really required on Linux variants?

2)How can I see the details of what UBUNTU trying to download?

3)If there are such downloads, does Ubuntu maintain a log of such events or downloads.

4)Is there any way to know to which location is the files being downloaded?

5)What should I do to prevent such downloads which are not initiated by the User by a command or other means.

I am using a 3G service to connect to the Internet and these unknown sending/recieving of bytes is taxing my bandwidth on the Internet.


Operating system : Ubuntu 11.10. Upgraded from Ubuntu 11.04 via update manager
Browser:Mozilla 17.0.1


Thank you!