Ping Range from Terminal in OS X

nmap is the key...

If you do not have nmap installed, then I suggest installing it. The best way to get this installed is using a program called fink.

Note: You'll need to enable root user for nmap to work and know root password

Once installed, open a terminal window and type

fink install nmap

(you'll have to type in your password just like you do when you install any program)

Now that nmap is installed, run the following command

nmap -sP -T Insane 192.168.1.1-254

You should get an output like:

Starting nmap V. 3.00 ( http://www.insecure.org/nmap/ )

Host (192.168.0.1) appears to be up.

Host (192.168.0.100) appears to be up.

Host (192.168.0.110) appears to be up.

Nmap run completed -- 254 IP addresses (3 hosts up) scanned in 3 second

You can also run

nmap -T4 -A -v 192.168.250.0/24

Check out the GUI version of nmap for your Mac called Zenmap (most excellent tool)