IPcalc

Ipcalc is a command-line tool which allows the user to get useful data from a ip and a netmask.

Ipcalc returns the network address, netmask, network address in CIDR notation, min/max IP addresses, broadcast address and the number of hosts of network.

Ipcalc usage is:

Usage: ipcalc [options] 
[[/]] [NETMASK]

A example could be:

$ ipcalc 10.0.0.28 255.255.255.0
Address:   10.0.0.28            00001010.00000000.00000000. 00011100
Netmask:   255.255.255.0 = 24   11111111.11111111.11111111. 00000000
Wildcard:  0.0.0.255            00000000.00000000.00000000. 11111111
=>
Network:   10.0.0.0/24          00001010.00000000.00000000. 00000000
HostMin:   10.0.0.1             00001010.00000000.00000000. 00000001
HostMax:   10.0.0.254           00001010.00000000.00000000. 11111110
Broadcast: 10.0.0.255           00001010.00000000.00000000. 11111111
Hosts/Net: 254                   Class A, Private Internet

Ipcalc has been available in Debian at least since v3.1 (’Sarge’) and in Ubuntu since Warty. apt-get install ipcalc will install it for you.