nmap -sn -n --unprivileged 10.0.1.0/24 note: "unprivileged" is important because if you omit it, nmap tends to spurious report almost every host as "up". it does this because it uses raw sockets and will interpret some firewall response packets as ping responses from the host; if you use unprivileged, nmap is forced to use the normal system calls for sending a ping and will only get a reply if there really is one.