I have Windows XP service pack 2 with a Verizon DSL line and a
Versalink modem.  Recently, the activity light has been blinking
constantly even when the computer is idle.  Is there any website or
software that would conveniently show me what activity is going on
from where on my Internet connection?  I don't know if it's malicious
or not but I would be curious to find out what is going on as it
happens.

Hello jdb2115-ga,

I have listed some software below that will allow you to figure out if
and how your computer is using the network. I have tried to choose
software that is easy to use and simple as some of the software in
this category can be quite complicated:

Look@Lan Network Monitor
Download at: http://www.lookatlan.com/
Status: freeware

Network Traffic Monitor
Download at: http://www.nicocuppen.com/download.php 
Status: 7 day free trial

Watchdog
Download at: http://www.niftytools.com/HTML/wdevalfm.htm
Status: 7 day free trial

For a quick way to check connections on your computer without installing software:
1. Click Start -> Run
2. Type in cmd and click OK
3. Type in netstat -a
4. Press enter

Please let me know if you require further clarification. Good luck!

tisme-ga

You could try the trial version of sunbelt kerio personal firewall
(google it), this logs data packets by web address coming into your
computer in a list, and should show if you are receiving a large amout
of stuff you don't want.

Perhaps it could be your own mailbox e.g Outlook Express checking for
mail (To check how often look under Tools - Options - General).
Or your computer could be checking for updates.
I have Windows XP Home Edition SP2 and get these updates: Windows
Updates, Program Updates, HP Solution Center, Anti-Virus.
Mind you I have just checked under scheduled tasks (in control panel) and
found only the anti-virus is set to automatically check for updates
and that is for every 4 hours.
Hope this is useful.

If you are concerned about your machine(s) making any connections out
to the internet.

* Simply open a command prompt (start --> run --> Type "cmd" (without quotes)
* type netstat >c:\netstat.txt
* In the morning. Open that file and peruse it manually. Try to see if
there is a pattern when it comes to different i.p addresses.

Most probably it is "Windows updates" kicking in and downloading
updates as such. Or some other application that makes outgoing
connections.

To find out information about a requisite i.p address. Type that i.p
address on the "whois" information on http://www.arin.net . and that
will tell you which company that i.p belongs to.

for more information about the netstat command type ---> "etstat /?"
(again withouth quotes)

hope this helps. 


p.s: If you are concerned about your machine making incoming and
outcoming connections. Try installing a software version of the many
available firewall versions out there.

oops slight correction

netstat 30 >c:\netstat.txt   


this will basically keep the netstat command running on your machine,
every 30 seconds. The output of the command is goint to the
"netstat.txt" file, which in this case we have specified to be created
and reside on the root of drive C:

to kill the netstat. simply type Ctrl+c
or close the command prompt. This will not affect the content of the
netstat.txt file.

netstat.exe and see ip connections.

Web Query to Reverse Lookup Country, State, City, Latitude, Longitude
and ISP by IP address in http://www.ip2location.com/free.asp.

another way is a firewall ( zone alarm ) or any sniffer (as
http://descargas.vnunet.es/descargas/redes/ultra+network+analyzer/_309.html)

It is most likely Broadcast traffic that your modem is showing as activity. 
this traffic can be from other people on your IP subnet.