IP Subnet Calculator

This module calculates optimal subnet masks for non-standard IP ranges, e.g. 5.4.3.21 - 6.7.8.9

View demo

What does it do?

• Calculates subnet masks for standard and non-standard IP ranges. For example, 10.0.0.5 - 10.0.0.23 will result in 10.0.0.5/32, 10.0.0.6/31, 10.0.0.8/29, 10.0.0.16/29.
• Calculates CIDR prefixes from subnet masks, e.g. 10.0.0.5/255.255.128.0 will result in 10.0.0.0/17.
• Calculates subnet masks from CIDR prefixes, e.g. 10.0.0.5/17 will result in 255.255.128.0.

Support

• Node.js
• Direct browser use

Installation

> npm install ip-subnet-calculator

Node.js

import * as IPSubnetCalculator from 'ip-subnet-calculator';
// or: const IPSubnetCalculator = require('ip-subnet-calculator');

console.log(IPSubnetCalculator.isIp('127.0.0.1')); // true
console.log(IPSubnetCalculator.toDecimal('127.0.0.1')); // 2130706433

console.log(IPSubnetCalculator.calculate('5.4.3.21', '6.7.8.9'));

Direct browser use

<script src='lib/ip-subnet-calculator.browser.js'></script>

<script>
    console.log(IPSubnetCalculator.isIp( 127.0.0.1')); // true
    console.log(IPSubnetCalculator.toDecimal('127.0.0.1')); // 2130706433
    
    console.log(IPSubnetCalculator.calculate( '5.4.3.21', '6.7.8.9' ));
</script>

API

IPSubnetCalculator.calculate(ipStart, ipEnd)

Calculates an optimal set of IP masks for the given IP address range.

ipStart (string|number) Lowest IP in the range to be calculated in string (123.123.123.0) or numeric (2071689984) format.

ipEnd (string|number) Highest IP (inclusive) in the range to be calculated in string (123.123.123.255) or numeric (2071690239) format.

The function returns null in case of an error. Otherwise, an array containing one or more subnet masks is returned:

const result = [
  {
    ipLow              : 2071689984,
    ipLowStr           : "123.123.123.0",
    ipHigh             : 2071690239,
    ipHighStr          : "123.123.123.255",
    prefixMask         : 4294967040,
    prefixMaskStr      : "255.255.255.0",
    prefixSize         : 24,
    invertedMask       : 255,
    invertedMaskStr    : "0.0.0.255",
    invertedMaskSize   : 8
  },
  
  ...
];

Each object in question contain the following properties:

Property	Use
ipLow	Decimal representation of the lowest IP address in the range
ipLowStr	String representation of the lowest IP address in the range
ipHigh	Decimal representation of the highest IP address in the range
ipHighStr	String representation of the highest IP address in the range
prefixMask	Decimal representation of the prefix (subnet) mask
prefixMaskStr	String representation of the prefix (subnet) mask
prefixSize	Size of the prefix (subnet) mask in bits
invertedMask	Decimal representation of the inverted prefix mask
invertedMaskStr	String representation of the inverted prefix mask
invertedSize	Size of the inverted prefix max in bits

IPSubnetCalculator.calculateSubnetMask(ip, prefixSize)

Calculates a subnet mask from CIDR prefix.

ip (string|number) IP address in string or numeric format

prefixSize (number) Number of relevant bits in the subnet mask

The function returns an object containing full description of the IP range, as described in IPSubnetCalculator.calculate().

IPSubnetCalculator.calculateCIDRPrefix(ip, subnetMask)

Calculates a CIDR prefix from subnet mask.

ip (string|number) IP address in string or numeric format

subnetMask (string|number) IP subnet mask in string or numeric format

The function returns an object containing full description of the IP range, as described in IPSubnetCalculator.calculate().

Test Functions

IPSubnetCalculator.isIp(ipStr)

Tests whether string is an IP address.

ipStr (string) A string

The function returns a true if the string is an IP address, false otherwise.

IPSubnetCalculator.isDecimalIp(ipNum)

Tests whether ipNum is a decimal IP address.

ipNum (number) A number

The function returns a true if the number is an IP address, false otherwise.

Conversion Functions

IPSubnetCalculator.toDecimal(ip)

Calculates a decimal integer from an string IP address.

ip (string|number) IP address in string format

The function returns a decimal representation of an IP address as an integer. If a valid numeric representation of an IP is passed to this function, it is returned unmodified.

If an invalid value is passed to the function, it will throw an Error object.

IPSubnetCalculator.toString(num)

num (number|string) Decimal representation of an IP address.

The function returns an IP address as a string. If a valid string representation of an IP is passed to this function, it is returned unmodified.

If an invalid value is passed to the function, it will throw an Error object.

License

MIT