Send a ping to each IP on a subnet

Question

Is there a command line based way to send pings to each computer in a subnet? Like

for(int i = 1; i < 254; i++)     ping(192.168.1.i); 

to enforce arp resolution?

Answer 1

Not all machines have nmap available, but it's a wonderful tool for any network discovery, and certainly better than iterating through independent ping commands.

 $ nmap -n -sP 10.0.0.0/24  Starting Nmap 4.20 ( http://insecure.org ) at 2009-02-02 07:41 CST Host 10.0.0.1 appears to be up. Host 10.0.0.10 appears to be up. Host 10.0.0.104 appears to be up. Host 10.0.0.124 appears to be up. Host 10.0.0.125 appears to be up. Host 10.0.0.129 appears to be up. Nmap finished: 256 IP addresses (6 hosts up) scanned in 2.365 seconds 

Answer 2

I would suggest the use of fping with the mask option, since you are not restricting yourself in ping.

fping -g 192.168.1.0/24 

The response will be easy to parse in a script:

192.168.1.1 is alive 192.168.1.2 is alive 192.168.1.3 is alive 192.168.1.5 is alive ... 192.168.1.4 is unreachable 192.168.1.6 is unreachable 192.168.1.7 is unreachable ... 

Note: Using the argument -a will restrict the output to reachable ip addresses, you may want to use it otherwise fping will also print unreachable addresses:

fping -a -g 192.168.1.0/24 

From man:

fping differs from ping in that you can specify any number of targets on the command line, or specify a file containing the lists of targets to ping. Instead of sending to one target until it times out or replies, fping will send out a ping packet and move on to the next target in a round-robin fashion.

More info: http://fping.org/