find all active IP addresses in a network

nmap -sP; arp -n | grep "192.168.1.[0-9]* *ether"
You send a unicast ICMP packet to each host. Many firewalls will drop that ICMP. However, in order to send the ICMP, you'll have first done an ARP request and the remote machine is unlikely to ignore that, so the computer will be in your ARP table.
Sample Output             ether   00:0b:db:7f:c1:4c   C                     eth0            ether   00:15:60:9a:76:71   C                     eth0             ether   00:15:60:5a:6b:0c   C                     eth0            ether   00:12:3f:27:a1:34   C                     eth0              ether   00:1e:c9:b0:3a:96   C                     eth0

By: gavinmc
2010-04-12 14:36:15

What do you think?

Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

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