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# cidr
 [](https://pkg.go.dev/github.com/bschaatsbergen/cidr)
Simplifies IPv4/IPv6 CIDR network prefix management with counting, overlap checking, explanation, and subdivision.
## Brew
To install cidr using brew, simply run:
```sh
brew install cidr
```
## Debian (Trixie and newer) & Ubuntu (Oracular and newer)
To install cidr using apt, simply run:
```sh
apt install cidr
```
## Binaries
You can download the [latest binary](https://github.com/bschaatsbergen/cidr/releases/latest) for Linux, MacOS, and Windows.
## Examples
Using `cidr` is very simple.
### Explain a CIDR range
To get more information on a CIDR range:
```
$ cidr explain 10.0.0.0/16
Base Address: 10.0.0.0
Usable Address Range: 10.0.0.1 to 10.0.255.254 (65,534)
Broadcast Address: 10.0.255.255
Addresses: 65,536
Netmask: 255.255.0.0 (/16 bits)
```
This also works with IPv6 CIDR ranges, for example:
```
$ cidr explain 2001:db8:1234:1a00::/110
Base Address: 2001:db8:1234:1a00::
Usable Address Range: 2001:db8:1234:1a00:: to 2001:db8:1234:1a00::3:ffff (262,142)
Addresses: 262,144
Netmask: ffff:ffff:ffff:ffff:ffff:ffff:fffc:0 (/110 bits)
```
### Check whether an address belongs to a CIDR range
To check if a CIDR range contains an IP:
```
$ cidr contains 10.0.0.0/16 10.0.14.5
true
```
This also works with IPv6 addresses, for example:
```
$ cidr contains 2001:db8:1234:1a00::/106 2001:db8:1234:1a00::
true
```
### Count
To get a count of all addresses in a CIDR range:
```
$ cidr count 10.0.0.0/16
65536
```
This also works with a IPv6 CIDR range, for example:
```
$ cidr count 2001:db8:1234:1a00::/106
4194304
```
Or with a large prefix like a point-to-point link CIDR range:
```
$ cidr count 172.16.18.0/31
2
```
### CIDR range intersection
To check if a CIDR range overlaps with another CIDR range:
```
$ cidr overlaps 10.0.0.0/16 10.0.14.0/22
true
```
This also works with IPv6 CIDR ranges, for example:
```
$ cidr overlaps 2001:db8:1111:2222:1::/80 2001:db8:1111:2222:1:1::/96
true
```
### CIDR division
To divide a CIDR range into N distinct networks:
```
$ cidr divide 10.0.0.0/16 9
10.0.0.0/20
10.0.16.0/20
10.0.32.0/20
10.0.48.0/20
10.0.64.0/20
10.0.80.0/20
10.0.96.0/20
10.0.112.0/20
10.0.128.0/20
```
This also works with IPv6 CIDR ranges, for example:
```
$ cidr divide 2001:db8:1111:2222:1::/80 9
2001:db8:1111:2222:1::/84
2001:db8:1111:2222:1:1000::/84
2001:db8:1111:2222:1:2000::/84
2001:db8:1111:2222:1:3000::/84
2001:db8:1111:2222:1:4000::/84
2001:db8:1111:2222:1:5000::/84
2001:db8:1111:2222:1:6000::/84
2001:db8:1111:2222:1:7000::/84
2001:db8:1111:2222:1:8000::/84
```
## Contributing
Contributions are highly appreciated and always welcome.
Have a look through existing [Issues](https://github.com/bschaatsbergen/cidr/issues) and [Pull Requests](https://github.com/bschaatsbergen/cidr/pulls) that you could help with.
|
