ipcalc
Installation
On ubuntu derivatives, as expected, sudo apt install ipcalc does the job.
Also available on macos via usual brew.
Use Examples
Display info on cidr 10.8.0.0/20:
$ ipcalc 10.8.0.0/20
Address: 10.8.0.0 00001010.00001000.0000 0000.00000000
Netmask: 255.255.240.0 = 20 11111111.11111111.1111 0000.00000000
Wildcard: 0.0.15.255 00000000.00000000.0000 1111.11111111
=>
Network: 10.8.0.0/20 00001010.00001000.0000 0000.00000000
HostMin: 10.8.0.1 00001010.00001000.0000 0000.00000001
HostMax: 10.8.15.254 00001010.00001000.0000 1111.11111110
Broadcast: 10.8.15.255 00001010.00001000.0000 1111.11111111
Hosts/Net: 4094 Class A, Private Internet
Split the above cidr into three /24 subnets:
$ ipcalc 10.8.0.0/20 --s 128 128 128
Address: 10.8.0.0 00001010.00001000.0000 0000.00000000
Netmask: 255.255.240.0 = 20 11111111.11111111.1111 0000.00000000
Wildcard: 0.0.15.255 00000000.00000000.0000 1111.11111111
=>
Network: 10.8.0.0/20 00001010.00001000.0000 0000.00000000
HostMin: 10.8.0.1 00001010.00001000.0000 0000.00000001
HostMax: 10.8.15.254 00001010.00001000.0000 1111.11111110
Broadcast: 10.8.15.255 00001010.00001000.0000 1111.11111111
Hosts/Net: 4094 Class A, Private Internet
1. Requested size: 128 hosts
Netmask: 255.255.255.0 = 24 11111111.11111111.11111111. 00000000
Network: 10.8.0.0/24 00001010.00001000.00000000. 00000000
HostMin: 10.8.0.1 00001010.00001000.00000000. 00000001
HostMax: 10.8.0.254 00001010.00001000.00000000. 11111110
Broadcast: 10.8.0.255 00001010.00001000.00000000. 11111111
Hosts/Net: 254 Class A, Private Internet
2. Requested size: 128 hosts
Netmask: 255.255.255.0 = 24 11111111.11111111.11111111. 00000000
Network: 10.8.1.0/24 00001010.00001000.00000001. 00000000
HostMin: 10.8.1.1 00001010.00001000.00000001. 00000001
HostMax: 10.8.1.254 00001010.00001000.00000001. 11111110
Broadcast: 10.8.1.255 00001010.00001000.00000001. 11111111
Hosts/Net: 254 Class A, Private Internet
3. Requested size: 128 hosts
Netmask: 255.255.255.0 = 24 11111111.11111111.11111111. 00000000
Network: 10.8.2.0/24 00001010.00001000.00000010. 00000000
HostMin: 10.8.2.1 00001010.00001000.00000010. 00000001
HostMax: 10.8.2.254 00001010.00001000.00000010. 11111110
Broadcast: 10.8.2.255 00001010.00001000.00000010. 11111111
Hosts/Net: 254 Class A, Private Internet
Needed size: 768 addresses.
Used network: 10.8.0.0/22
Unused:
10.8.3.0/24
10.8.4.0/22
10.8.8.0/21
IPv4 Address Ranges
From RFC 5735:
| Address Block | Present Use | Reference |
|---|---|---|
| 0.0.0.0/8 | “This” Network | RFC 1122, Section 3.2.1.3 |
| 10.0.0.0/8 | Private-Use Networks | RFC 1918 |
| 100.64.0.0/10 | Shared address space | RFC 6598 |
| 127.0.0.0/8 | Loopback | RFC 1122, Section 3.2.1.3 |
| 169.254.0.0/16 | Link Local | RFC 3927 |
| 172.16.0.0/12 | Private-Use Networks | RFC 1918 |
| 192.0.0.0/24 | IETF Protocol Assignments | RFC 5736 |
| 192.0.2.0/24 | TEST-NET-1 | RFC 5737 |
| 192.88.99.0/24 | 6to4 Relay Anycast | RFC 3068 |
| 192.168.0.0/16 | Private-Use Networks | RFC 1918 |
| 198.18.0.0/15 | Network Interconnect, Device Benchmark Testing | RFC 2544 |
| 198.51.100.0/24 | TEST-NET-2 | RFC 5737 |
| 203.0.113.0/24 | TEST-NET-3 | RFC 5737 |
| 224.0.0.0/4 | Multicast | RFC 3171 |
| 240.0.0.0/4 | Reserved for Future Use | RFC 1112, Section 4 |
| 255.255.255.255/32 | Limited Broadcast | RFC 919, Section 7, RFC 922, Section 7 |