Check which ports are open to the outside world. Helps make sure that your firewall rules are working as intended.
One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.
from below link
#!/bin/sh a=0 while [ $a -lt 10 ] do echo $a if [ $a -eq 5 ] then break fi a=`expr $a + 1` done