Network Discovery/Map
 

Hi,

I'm installing a server at a small medical clinic where a LAN is already in place.
The guys who installed the LAN have closed down their company and have gone their own ways, leaving no map of the network, so we're having some issues knowing what's connected to what in terms of their LAN - some PC's have the 192.168.0.xxx range while other have the 192.168.1.xxx range.

I've got Ubuntu Server 12.04 as the OS on the server I've built and also have installed Nagios3 and Webmin.
What "tools" can I use to do a network discovery/network map - I know Zabbix has this feature built in, but I don't want to put anything more than what's already on, on the server.

Anything in terms of Nagios or Webmin?

I used Passifist tool for same for BackTrack OS. Not sure if available in Ubuntu.

Thanks

If you have nmap installed, that might be a good option. Scanning a /24 segment is reasonably fast (not lightning fast, but tolerable), but I wouldn't want to try any massive address space. OTOH, there might be reasons why that doesn't find anything, depending on how paranoid the original network set-up was.

You might also want to try capturing some data. Wireshark would be my normal choice, but as that's a GUI app, something like tcpdump is probably more appropriate.