Nmap -sS will do a SYN and look for an ACK, but it will not connect. If you use -sT it will connect.

Nmap -sP for a ping sweep.

Use nmap to get a report: nmap -O -sV -sC -vv -oA printer --stylesheet=nmap.xsl <host(s)>

While scans are going on, you can use these KEY bindings: If you press these keys with SHIFT it does the oppisit.