If you need to run a program that gathers information from the "Virtual Network" then *IMO* your first choice should be your host OS, in my case, Windows.
First you need to install the loopback device via
You will then be prompted by the Hardware Wizzard!
Common Hardware Types >> Network Adapters
Choose Microsoft >> Microsoft KM-TEST Loopback Adapter
Now lets fire up GNS3!
Just drag over a "Cloud" appliance and right click >> configure
Under Cloud select the new Cloud appliance and under the Generic Ethernet NIO drop-down select Loopback *Or whatever the adapter is called, it might be ethernet#, check out how to make a shortcut to Network Adapters for easy reference, and IMO you should change it to be called loopback for easier reference.*
You are now ready to go! If you run a program in Windows you can bind it to the loopback and it can interact with the virtual network, or if you use cmd.exe to ping the virtual network it should work as long as it doesn't conflict with any other adapters currently in use by windows