I actually spent the last 4 Hours on researching this problem, however didn't manage to find a working answer to my problem.
Actually it is quite easy, I did a network scan with nmap for alive hosts. This however didn't give me the Hostname of that PC, which I need for my program.

In my research I only found a few solutions, the most were questions how to change the own Hostname:

Use nslookup, dig or hosts. Doesn't work as the local PCs are obviously not registered in the WWW DNS Server.
AutoScan, no results either
Ping -a <IP>, nope.

So I think this should be fairly easy, as I basically can do this with my smartphone, but somehow it struggles with BT5.

And regarding Smartphones, is there a backtrack 5 tool that can scan for barbour services?