Express-ipfilter NPM

express-ipfilter: A light-weight IP address based filtering system

This package provides easy IP based access control. This can be achieved either by denying certain IPs and allowing all others, or allowing certain IPs and denying all others.

Installation

Recommended installation is with npm. To add express-ipfilter to your project, do:

npm install express-ipfilter

Usage with Express

Denying certain IP addresses, while allowing all other IPs:

// Init dependencies
const express = require('express')
const ipfilter = require('express-ipfilter').IpFilter

// Deny the following IPs
const ips = ['127.0.0.1']

// Create the server
app.use(ipfilter(ips))
app.listen(3000)

Allowing certain IP addresses, while denying all other IPs:

// Init dependencies
// Init dependencies
const express = require('express')
const ipfilter = require('express-ipfilter').IpFilter

// Allow the following IPs
const ips = ['127.0.0.1']

// Create the server
app.use(ipfilter(ips, { mode: 'allow' }))

module.exports = app

Using CIDR subnet masks for ranges:

const ips = ['127.0.0.1/24']

// Create the server
app.use(ipfilter(ips, { mode: 'allow' }))

module.exports = app

Using IP ranges:

const ips = [['127.0.0.1', '127.0.0.10']]

// Create the server
app.use(ipfilter(ips, { mode: 'allow' }))

module.exports = app

Using a function to get Ips:

const ips = function() {
  return ['127.0.0.1']
}

// Create the server
app.use(ipfilter(ips, { mode: 'allow' }))

module.exports = app

Using wildcard ip ranges and nginx forwarding:

  let allowlist_ips = ['10.1.*.*', '123.??.34.8*'] // matches '10.1.76.32' and '123.77.34.89'

  let clientIp = function(req, res) {
    return req.headers['x-forwarded-for'] ? (req.headers['x-forwarded-for']).split(',')[0] : ""
  }
  
  app.use(
    ipFilter({
      detectIp: clientIp,
      forbidden: 'You are not authorized to access this page.',
      filter: allowlist_ips,
    })
  )

Error Handling

When an IP is denied, an IpDeniedError will be thrown by the middleware. If you do not handle the error, it will cause your app to crash due to an unhandled exception. Here is an example of how to handle the error, which can also be found in the example app:

if (app.get('env') === 'development') {
  app.use((err, req, res, _next) => {
    console.log('Error handler', err)
    if (err instanceof IpDeniedError) {
      res.status(401)
    } else {
      res.status(err.status || 500)
    }

    res.render('error', {
      message: 'You shall not pass',
      error: err
    })
  })
}

You will need to require the IpDeniedError type in order to handle it.

Options

Property	Description	Type	Default
mode	whether to deny or allow to the IPs provided	string	deny
log	console log actions	boolean	true
logLevel	level of logging (all,deny,allow)	string	all
excluding	routes that should be excluded from ip filtering	array	[]
detectIp	define a custom function that takes an Express request object and returns an IP address to test against	function	built-in detection
trustProxy	This setting is implemented using the proxy-addr package. Check the documentation for the trust parameter.	boolean, array, string, number, function	false

A note on detectIp

If you need to parse an IP address in a way that is not supported by default, you can write your own parser and pass that to ipfilter.

const customDetection = req => {
  var ipAddress

  ipAddress = req.connection.remoteAddress.replace(/\//g, '.')

  return ipAddress
}

ipfilter(ips, { detectIp: customDetection })