@gibme/arp

A simple, cross-platform ARP helper for Node.js. Give it an IP address on your local network and it'll hand back the MAC address — no native modules, no fuss.

Works on Linux, macOS, and Windows.

Installation

yarn add @gibme/arp
# or
npm install @gibme/arp
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Requires Node >= 20.

Quick Start

import ARP from '@gibme/arp';

// Look up a MAC address by IP
const mac = await ARP.lookup('192.168.1.1');
console.log(mac); // e.g. "AA:BB:CC:DD:EE:FF"
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API

ARP.lookup(ip, separator?)

Resolves an IP address to a MAC address on your local network. It pings the target first (to make sure it's in the ARP table), then reads the result from the system ARP cache.

• ip — the IPv4 or IPv6 address to look up
• separator — character between MAC octets (defaults to :)
• returns — an uppercase MAC string like AA:BB:CC:DD:EE:FF
• throws — if the IP is invalid or the address isn't found

await ARP.lookup('192.168.1.1');       // "AA:BB:CC:DD:EE:FF"
await ARP.lookup('192.168.1.1', '-');  // "AA-BB-CC-DD-EE-FF"
await ARP.lookup('192.168.1.1', '');   // "AABBCCDDEEFF"
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ARP.get_gateway_ipv4()

Returns your default gateway's IPv4 address, or undefined if one isn't available. Handy for discovering the local router so you can pass it straight into lookup().

const gateway = await ARP.get_gateway_ipv4();
if (gateway) {
    const mac = await ARP.lookup(gateway);
    console.log(`Router MAC: ${mac}`);
}
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ARP.get_gateway_ipv6()

Same as above, but for IPv6.

Documentation

Full generated docs are available at https://gibme-npm.github.io/arp/.