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Network Calculator

netcalc <ADDRESS/LEN | NETWORK NETMASK> [split <1-32 | 64-128>]

Description

netcalc is a network calculator that takes an IP address and a subnet mask, or an IP address and prefix mask in CIDR notation, and then returns information about the subnet. Both IPv4 and IPv6 is supported.

A subnet can be entered in two ways:

  • 192.168.2.0 255.255.255.0: traditional IPv4 'address netmask' style
  • 192.168.2.0/24: modern prefix length, same also for IPv6

An optional split LEN can be given as argument, the new length value must be bigger than the current prefix length. See example below.

Examples

Its most commonly used features are to understand how many addresses an IP subnet has, what the broadcast address is, first and last usable address.

admin@example:/> netcalc 192.168.2.0/24
Address  : 192.168.2.0          11000000.10101000.00000010. 00000000
Netmask  : 255.255.255.0 = 24   11111111.11111111.11111111. 00000000
Wildcard : 0.0.0.255            00000000.00000000.00000000. 11111111
=>
Network  : 192.168.2.0/24       11000000.10101000.00000010. 00000000
HostMin  : 192.168.2.1          11000000.10101000.00000010. 00000001
HostMax  : 192.168.2.254        11000000.10101000.00000010. 11111110
Broadcast: 192.168.2.255        11000000.10101000.00000010. 11111111
Hosts/Net: 254                   Class C, Private network (RFC1918)

Another common use-case is for IP subnetting, i.e., using only as many addresses for an IP subnet as needed. Example, to split the above /24 in four:

admin@example:/> netcalc 192.168.2.0/24 split 26
Address  : 192.168.2.0          11000000.10101000.00000010. 00000000
Netmask  : 255.255.255.0 = 24   11111111.11111111.11111111. 00000000
Wildcard : 0.0.0.255            00000000.00000000.00000000. 11111111
=>
Network  : 192.168.2.0/24       11000000.10101000.00000010. 00000000
HostMin  : 192.168.2.1          11000000.10101000.00000010. 00000001
HostMax  : 192.168.2.254        11000000.10101000.00000010. 11111110
Broadcast: 192.168.2.255        11000000.10101000.00000010. 11111111
Hosts/Net: 254                   Class C, Private network (RFC1918)

[Split network/26]
Network  : 192.168.2.0   - 192.168.2.63     Netmask  : 255.255.255.192
Network  : 192.168.2.64  - 192.168.2.127    Netmask  : 255.255.255.192
Network  : 192.168.2.128 - 192.168.2.191    Netmask  : 255.255.255.192
Network  : 192.168.2.192 - 192.168.2.255    Netmask  : 255.255.255.192