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

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

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

npm install express-ipfilter

Usage with Express

NOTE: Starting with version 0.1.0, allow forwarded IP addresses through headers (forward, Cloudflare, Codio) are disabled by default. You must explicitly enable them by adding them to the allowedHeaders list.

Blacklisting certain IP addresses, while allowing all other IPs:

// Init dependencies 
var express = require('express'),
    ipfilter = require('express-ipfilter').IpFilter;
// Blacklist the following IPs 
var ips = [''];
// Create the server 

Whitelisting certain IP addresses, while denying all other IPs:

// Init dependencies 
// Init dependencies 
var express = require('express'),
    ipfilter = require('express-ipfilter').IpFilter;
// Whitelist the following IPs 
var ips = [''];
// Create the server 
app.use(ipfilter(ips, {mode: 'allow'}));
module.exports = app;

Using CIDR subnet masks for ranges:

var ips = [''];
// Create the server 
app.use(ipfilter(ips, {mode: 'allow'}));
module.exports = app;

Using IP ranges:

var ips = [['','']];
// Create the server 
app.use(ipfilter(ips, {mode: 'allow'}));
module.exports = app;

Using a function to get Ips:

var ips = function() { return ['']; };
// Create the server 
app.use(ipfilter(ips, {mode: 'allow'}));
module.exports = app;

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(function(err, req, res, _next) {
    console.log('Error handler', err);
    if(err instanceof IpDeniedError){
      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.


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
allowedHeaders an array of strings for header names that are acceptable for retrieving an IP address array []
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

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.

function customDetection(req){
  var ipAddress;

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

  return ipAddress;

ipfilter(ids, {detectIp: customDetection});


See the CONTRIBUTING.MD document for more information on contributing.

Building from source

You can run grunt to build the source. This will run eslint and babel against src/ipfilter.js.

There is an included example project that will load the package from the local build for testing.

Running Tests

Run tests by using

grunt test

This will run eslint,babel, and mocha and output coverage data into coverage. Any pull request you submit needs to be accompanied by a test.



  • Fixes critical bug that allowed access when ips is empty and mode == 'allow'.
  • Adds minor speed improvements for middleware.
  • Minor spelling and documentation fixes in README


  • Adds the ability to pass IPs by function so that we can dynamically retrieve white/black listed addresses.


  • Minor change to the Contributing Guidelines to include updating the version numbers


  • Added fields status and statusCode to the IpDeniedError object, which both equal 403.


  • For IPv4 addresses that have a port (as experienced with Azure web apps), the port is now stripped before comparing it with the contents of the whitelist or blacklist. Fixes issue #49.


  • Fixed a bug that sent all logging through instead of just denied requests


  • Added a customization point for IP detection
  • Fixed a bug with IPv4 over IPv6


  • Add log level property.


  • Changed how error handling works
  • Removed settings for specific vendor ip addresses and added allowedHeaders to support those header-based IP addresses.
  • You must now specifically require IpFilter, i.e. var ipfilter = require('express-ipfilter').IpFilter;
  • If you want to handle errors you must require the error type as well var IpDeniedError = require('express-ipfilter').IpDeniedError;


  • Added a favicon to the example to suppress the 404 error looking for it.


  • Changed default behavior of the library to disable reading forwarded IP headers. They must now be explicitly enabled.
  • Using res.send when a failure occurs to allow for different formats of errorMessage


  • Switched from netmask to range_check (uses ipaddr.js)
  • Added support for IPv6 CIDR
  • Fixed issue with mixed IPv4 and IPv6 rules


  • Added lib to version control


  • added codio x-real-ip header


  • Added IPv6 Support
  • Added build tools
  • Added test coverage and reporting


  • Added a setting to explicitly allow CloudFlare and Forwarded IPs. By default they are set to not allow these headers. Thanks to @longstone!



  • Fixing bug when array of CIDR blocks are used


  • Fixing bug when no IP address can be determined


  • Minor bug fix


  • Adding the ability to have exclusion urls


  • Diagnostic Options


  • Bug Fix for port logic


  • Added support for IPs with port numbers


  • Fixing deploy issues


  • Auto deploys for npm


  • Add support ip ranges.


  • Fixed a bug when using console output


  • Added ability to block by subnet mask (i.e.
  • Added tests for cidr functionality


  • Add tests
  • Update docs
  • Refactor, and restyle


  • First revision


BaM Interactive -