I am using Ubuntun 9.10. The default app to connect to the Internet is NetworkManager Applet 0.7.996 and I am using Firefox v3.5.6. I use a cable with modem for my Internet connection. Here's the problem. The cable modem is ON and showing proper indicators that it's ready and available. Firefox is up and running after I have connected to the Internet using NetworkManager to establish the Internet connection. Surfing, browsing, whatever all ok. I also have NetMonScreenlet v0.2 installed to watch upload/download status when connected. Now here's the rub. When I disconnect from the Internet, NetMonScreenlet and the data signal light in the back of my computer are still indicating "supposedly" data is being transferred .. to where I don't know. It may only be between the cable modem and the computer or worse, it may be going out to the world! The only time "no data" is being transferred is when the cable modem is turned off. I have shifted over from Windows XP Home to Ubuntu. I did not have this "problem" in Windows XP. In XP, when the connection was terminated with the modem still active, data stopped flowing. So, is there any way ... with the cable modem on ... to stop ANY data being passed? Another question ... is there GOOD network or connection manager app/utilitity (whatever) to replace this NetworkManager Applet that is default on my computer? Thanks.

A Linux OS is made up of many smaller programs that run in the background known as daemons. Even though you might not have an application open like Firefox, parts of the OS will still be connecting to the Internet to do things like check for updates or adjust the system time, while other daemons might be scanning the local network looking for file servers and other discoverable resources.

So seeing network activity is nothing to be worried about, and is perfectly normal. Linux is nothing like Windows, so you shouldn't be surprised when it doesn't behave the same way.

First, thanks for responding. Now, if the Internet connection has been terminated by disconnecting at the NetworkManager Applet why then is there any data being transferred? The only way to actually stop this is to turn off the cable modem also. With Windows, when the Internet connection was terminated, irregardless of whether or not there were any automatic operations that required the Internet connection, all data transfer stopped completely; even with the cable modem turned on. And, quite honestly, I don't really want anything running automatic on the Internet if it is at all possible. Please understand that I am not trying to compare the two OSs because I know they are not the same "animal".

Additional thought!! I have noticed that the cable modem indicator lights do not show anything being sent/received with the Internet connection terminated with the exception of the "hand-shaking" activity between the cable modem and the cable service provider. The cable modem is showing POWER, CABLE, and PC lights being lit only. Basically it is showing exactly what I would have seen in Windows as well. However, the data activity light on the back of the computer is flashing furiously at steady blinking pace. This is not so on Windows.

You may even see the activity light blink on the back of the NIC with the computer powered down. The NIC gets power from the network. Wake-on-lan uses this to power up the computer if the computer's MAC address is accessed.