Hello everyone.

I've been working with backtrack vulnerability testing for a while now (May i add BT5 is amazing, great job) and i would like to take my knowledge to the next step. So here is my question.

Okay so when you scan in a network with nmap (if you're on the same network) you can view everyone on the network and open ports. etc.

So i would like to know if i have an external IP address i need to scan, how would i get passed the router to see the computers on the network? I would use nessus for more evaluation.

One of the reasons i would love to learn this is my friend who lives half way across the world would like me to do some testing on his small business network. I can't go to him to do this so I'm going to try my best to do it from home. Any new tools would help me doing so?

Thanks for your time and if i didn't explain good enough feel free to let me know.