One-liner: How to scan a network for up & down hosts

Another network scanner.

For example, you want to find possible free IP-addresses in the 10.0.10.1 – 10.0.10.1 range:

for i in {1..10}; do (ip="10.0.10.$i"; up=`ping -n -q -W3 -c1 $ip | fgrep transmitted | sed -e 's/.*100%.*/down/' -e 's/.*0%.*/up/'`;name=`host $ip | awk '!/NXDOMAIN/{print $NF}'`; echo $ip $up $name)  2>/dev/null & done | sort -n -t. -k4

Result:

10.0.10.1 down
10.0.10.2 down
10.0.10.3 up host1.
10.0.10.4 down
10.0.10.5 down myhost2.internal.domain.
10.0.10.6 up nas3.
10.0.10.7 down laptop.
10.0.10.8 down
10.0.10.9 up switch2.
10.0.10.10 down printer.

See also: One-liner: how to do a ping sweep in bash