Hi,
I want to send ping (or other traffic) to my own IP address and have
it go out on the network.  Currently if i ping my own IP address the
operating system figures out that that is the same as local host. 
Then the OS pretends to have sent and received the ping.  But its only
pretending since the ping to my own IP address works even when the
network cable is disconnected.

This might be achieved by using a machine emulator such as VMware and
having the second OS set with a different IP (then ping the 'other'
machine).  This solution is sort of acceptable, but clunky.  $5 tip
for option that does not involve emulation with a second machine.

The OS of interest is Windows XP pro, Fedora Core 3 could be used, but
is not my first choice.

Answer criteria:
PC must be able to send itself packets (ping etc).
Solution should work when PC is attached to a router, and
*not* work when PC is disconnected.
Solution must work when a simple loopback connector is plugged into
the NIC, and *not* work when loopback is removed.
Can only involve 1 Ethernet card.
Thanks,
Steve

Have you tried pinging the external IP address of your computer? Like
if your computer's internal address is 192.168.1.10 and your external
is something like 128.195.40.67 or something, then ping the 128
address. That might do what you want it to do.

-rename your c:\windows\system32\drivers\etc\HOSTS  file to HOSTS.bak
(you may need to reboot if you make changes to this, I'm unsure)
-unplug your cable
-ping the IP address,  ie 192.168.1.18  not 127.0.0.1
ping 192.168.0.18

Hi,
Thank you for the comments.  

Using the external IP is quite interesting - i did not know such a
thing existed.  Unfortunately i cant have other devices on the line
during these tests.  A router might be tolerable, but a service
provider would cause issues.

I attempted the rename of the HOSTS file.  This did not work out. 
Latter i reassigned the IP address of localhost, which is in the hosts
file.  But windows appears to ignore whats in the hosts file when i
ping the localhost.  This is amusing since windows is the one who
identifies localhost as 127.0.01