SNMP-Scout

SNMP-Scout is a Node.js-based host discovery tool that uses SNMP to find hosts on a given subnet specified with a CIDR-formatted string.

Features

• Discover hosts using SNMP
• Streamed host discoveries
• Customizable discovery rules
• Support for multiple community strings
• Support for matching multiple OIDs
• CLI and Module

Installation

Install SNMP-Scout globally using npm:

npm install -g snmp-scout

Or install as a Node module using npm:

npm install --save snmp-scout

The example rules module (snmp-scout-rules.example.js) requires the net-snmp module for constants. The net-snmp module must be installed in the working directory for the module to be loaded. This is also needed for other modules that are imported/required by the rules module.

// snmp-scout-rules.js
const snmp = require('net-snmp')

This will create/update the package.json file and node_modules folder in the current working directory.

npm install net-snmp

Usage

CLI

Run SNMP-Scout from the command line:

snmp-scout --rules path/to/rules/file

Available options:

• -r, --rules <path-to-rules-file>: Specify a path to the discovery rules file - default: ./snmp-scout-rules.js -- see format below
• -c, --concurrency <number>: The maximum number of SNMP/UDP connections to make concurrently, default: 50
• -s, --stream: Output hosts as they are discovered
• -j, --json: Output to STDOUT in JSON format instead of a table
• -h, --help: Show help message and exit

As a module

You can also use SNMP-Scout as a module in your Node.js project:

const { discoverHosts } = require('snmp-scout');

const rules = [
  // Define your discovery rules here - see format below
];

// default concurrency
discoverHosts(rules).then(discoveredHosts => {
  // Process the discovered hosts
});

// specify concurrency
discoverHosts(rules, 100).then(discoveredHosts => {
  // Process the discovered hosts
});

discoverHosts() can also return a Readable stream:

var stream = discoverHosts(rules, options.concurrency, true);

stream.pipe(transformHost)
    .pipe(process.stdout)
    .on('error', (err) => {
      // ...
    });

// - or -

stream.on('data', (host) => { //... });

stream.on('end', () => { //... })

Host objects in discoveredHosts

var discoveredHosts = [{
  "ip": "192.168.1.10",
  "community": "public",
  "varbinds": [
    {
      "oid": "1.3.6.1.2.1.1.1.0",
      "type": 4,
      "value": "Linux server 5.10.0-8-amd64 #1 SMP Debian 5.10.46-4 (2021-08-03) x86_64"
    }
  ],
  "rule": { // rules[i] - a direct reference of the rule in the rules Array
    "name": "Linux Host",
    "community": ["public"],
    "oids": ["1.3.6.1.2.1.1.1.0"],
    "matchFunction": (ip, varbinds) => { ... }
  }
}]

Discovery Rules

When used as CLI, the rules file (default: ./snmp-scout-rules.js) should be a CommonJS module and export the rules in an Array like so:

module.exports = [
  {
    name: 'Rule Name',
    subnet: "192.168.0.0/24"
    community: ['public', 'private'],
    oids: ['1.3.6.1.2.1.1.1.0', '1.3.6.1.2.1.1.5.0'],
    matchFunction: (ip, varbinds) => {
      // Your matching logic here
      // Return true|false
    },
  },
  // ...
];

When imported as a module, the rules are passed to the discoverHosts(rules) function.

Contributing

Feel free to open issues or submit pull requests on the GitHub repository.

License

This project is licensed under the ISC License