Linux Command line tool to work with netmasks / CIDR notation [closed]
Solution 1:
ipcalc can do this, for example:
[kbrandt@kbrandt-opadmin: ~] ipcalc 192.168.1.1/24
Address: 192.168.1.1 11000000.10101000.00000001. 00000001
Netmask: 255.255.255.0 = 24 11111111.11111111.11111111. 00000000
Wildcard: 0.0.0.255 00000000.00000000.00000000. 11111111
=>
Network: 192.168.1.0/24 11000000.10101000.00000001. 00000000
HostMin: 192.168.1.1 11000000.10101000.00000001. 00000001
HostMax: 192.168.1.254 11000000.10101000.00000001. 11111110
Broadcast: 192.168.1.255 11000000.10101000.00000001. 11111111
Hosts/Net: 254 Class C, Private Internet
if you entered a subnet mask instead of CIDR, you will still see the /## CIDR number after 'Network:', so it goes both ways.
or with sipcalc:
[kbrandt@kbrandt-opadmin: ~] sipcalc 192.168.1.1/24 <23403@8:55>
-[ipv4 : 192.168.1.1/24] - 0
[CIDR]
Host address - 192.168.1.1
Host address (decimal) - 3232235777
Host address (hex) - C0A80101
Network address - 192.168.1.0
Network mask - 255.255.255.0
Network mask (bits) - 24
Network mask (hex) - FFFFFF00
Broadcast address - 192.168.1.255
Cisco wildcard - 0.0.0.255
Addresses in network - 256
Network range - 192.168.1.0 - 192.168.1.255
Usable range - 192.168.1.1 - 192.168.1.254
The Ubuntu Packages are ipcalc and sipcalc:
sudo apt-get install ipcalc
sudo apt-get install sipcalc
Solution 2:
netmask supports automatically figuring out minimal sets of subnets for a particular IP range, which I find to be handy. For example:
# netmask -c 10.32.0.0:10.255.255.255
10.32.0.0/11
10.64.0.0/10
10.128.0.0/9
Solution 3:
You could use the bash scripts located here for converting from cidr to mask and mask to cidr notation:
Here's a copy of what the scripts are, to ensure the answer is always available here:
mask2cdr ()
{
# Assumes there's no "255." after a non-255 byte in the mask
local x=${1##*255.}
set -- 0^^^128^192^224^240^248^252^254^ $(( (${#1} - ${#x})*2 )) ${x%%.*}
x=${1%%$3*}
echo $(( $2 + (${#x}/4) ))
}
cdr2mask ()
{
# Number of args to shift, 255..255, first non-255 byte, zeroes
set -- $(( 5 - ($1 / 8) )) 255 255 255 255 $(( (255 << (8 - ($1 % 8))) & 255 )) 0 0 0
[ $1 -gt 1 ] && shift $1 || shift
echo ${1-0}.${2-0}.${3-0}.${4-0}
}
so for example, running:
mask2cdr 255.255.255.255
returns 32