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cidr

GitHub release (latest SemVer) Go Reference

Simplifies IPv4/IPv6 CIDR network prefix management with counting, overlap checking, explanation, and subdivision.

Brew

To install cidr using brew, simply run:

brew install cidr

Debian (Trixie and newer) & Ubuntu (Oracular and newer)

To install cidr using apt, simply run:

apt install cidr

Binaries

You can download the latest binary 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 and Pull Requests that you could help with.