when you ping an ip, you are simply checking to see if anyone
is currently online using that ip. It's like making a phone call.
Ping will send a certain number of dummy data packets to the
ip number you tell it to ping and then wait for a reply. If the ping
is successful then somebody's at the other end. If no answer,
then nobody's home.
A network guy once told me that once he finds a rogue hacker
scanning him, then he (the network guy) will turn around and
ping the rogue to death. I don't know why, except maybe to
annoy the guy if he's even listening. I don't know. I'm still
trying to figure it all out.
There are many packet sniffers and network scanners available.
Some are ridiculously expensive. My favorite it Netscan Tools Pro.
There's also a program that will graphically traceroute an ip. I forget its name right now. I've used it a couple of times. I traced
one guy scanning me all the way back to Great Britain. Most
trace routes seem to end at the main routing or backbone
cities, like Atlanta, etc.
It's very interesting--for about an hour.