Live host discovery.
hping3
One of the most useful tool, provides control on type of packets sent (ICMP, TCP).
Ping sending 3 ICMP packets on port 80
Port 80 is not usually blocked on websites…
URL=www.google.com
hping3 -S $URL -p 80 -c 3ping
Ping sending 3 ICMP packets to the URL.
URL=www.google.com
ping $URL -c 3