transparent-proxy

Real transparent HTTP-Proxy-Server. Upstream your requests whatever you want!

Usage no npm install needed!

<script type="module">
  import transparentProxy from 'https://cdn.skypack.dev/transparent-proxy';
</script>

README

Intro

transparent-proxy extends the native net.createServer and it acts as a real transparent http-proxy.

This module was built on top of TCP-level to avoid header-stripping problem of nodejs http(s)-modules.

It allows to upstream client-request dynamically to other proxies, or to certain iFace, and more...

It supports Basic Proxy-Authentication.

Quick Start

Install

npm i transparent-proxy

Use

const ProxyServer = require('transparent-proxy');

//init ProxyServer
const server = new ProxyServer();

//starting server on port 8080
server.listen(8080, '0.0.0.0', function () {
    console.log('TCP-Proxy-Server started!', server.address());
});

Options Object

Param Type Description
options Object The options object.
[options.auth] Function Activate/Handle Proxy-Authentication. Returns or solves to Boolean.
[options.upstream] Function The proxy to be used to upstreaming requests. Returns String.
[options.tcpOutgoingAddress] Function The localAddress to use while sending requests. Returns String
[options.injectData] Function The edited data to upstream. Returns Buffer or string
[options.injectResponse] Function The edited response to return to connected client. Returns Buffer or string
[options.keys] Function The keys to use while handshake. It will work only if intercept is true. Returns Object or false
[options.verbose] Boolean Activate verbose mode.
[options.intercept] Boolean Activate interception of encrypted communications. False as default.

upstream, tcpOutgoingAddress, injectData & injectResponse Options

The options are functions having follow parameters:

Param Type Description
data Buffer The received data.
session Session Object containing info/data about Tunnel
  • upstream-Function need to return/resolve a String with format -> IP:PORT or USER:PWD@IP:PORT of used http-proxy. If 'localhost' is returned/resolved, then the host-self will be used as proxy.
  • tcpOutgoingAddress-Function need to return a String with format -> IP.

Note: These functions will be executed before first tcp-socket-connection is established.

  • injectData-Function need to return a String or buffer for the new spoofed data. This will be upstreamed as request.
  • injectResponse-Function need to return a String or buffer for the new received data.

Upstream to other proxies

If you don't want to use the host of active instance self, then you need to upstream connections to another http-proxy. This can be done with upstream attribute.

const ProxyServer = require('transparent-proxy');

const server = new ProxyServer({
    upstream: function () {
          return 'x.x.x.x:3128'; // upstream to other proxy
    }
});

//starting server on port 8080
server.listen(8080, '0.0.0.0', function () {
    console.log('TCP-Proxy-Server started!', server.address());
});

You can also use an async function to upstream your requests:

const ProxyServer = require('transparent-proxy');

const server = new ProxyServer({
    upstream: async function () {
         //make some async task before
         return 'x.x.x.x:3128'; // upstream to other proxy
    }
});

//starting server on port 8080
server.listen(8080, '0.0.0.0', function () {
    console.log('TCP-Proxy-Server started!', server.address());
});

The auth Function

This activate basic authorization mechanism. The Auth-function will be executed while handling Proxy-Authentications.

Param Type Description
username String The client username.
password String The client password
session Session Object containing info/data about Tunnel

Note: It needs to return True/False or a Promise that resolves to boolean (isAuthenticated).

const ProxyServer = require('transparent-proxy');

const server = new ProxyServer({
    auth: function (username, password) {
        return username === 'bar' && password === 'foo';
    }
});

//starting server on port 8080
server.listen(8080, '0.0.0.0', function () {
    console.log('TCP-Proxy-Server started!', server.address());
});

Interception

The callbacks injectData & injectResponse could be used to intercept/spoof communication. These functions are executed with the data and session arguments.

Intercepting HTTPS

The boolean attribute intercept allows to break SSL-Communication between Source & Destination.

This will activate Security-Alarm by most used browsers.

const uaToSwitch = 'curl/7.55.1';
const switchWith = 'My Super Fucking Spoofed UA!';

const server = new ProxyServer({
    intercept: true,
    verbose: true,
    injectData: (data, session) => {
        if (session.isHttps) {
            if (data.toString().match(uaToSwitch)) {
                return Buffer.from(data.toString()
                    .replace(uaToSwitch, switchWith));
            }
        }
        return data;
    }
});

curl -x localhost:8080 -k http://ifconfig.io/ua
curl/7.55.1

curl -x localhost:8080 -k https://ifconfig.me/ua
My Super Fucking Spoofed UA!

The keys Function

This function will work only if intercept is set to true.

If activated needs to return an Object {key:'String', cert:'String'} like native tls_connect_options.key & tls_connect_options.cert or false statement.

If no object is returned, then default keys will be used to update communication.

Param Type Description
session Session Object containing info/data about Tunnel

Note: This function will be executed before TLS-Handshake.

Session-Instance

The Session-Instance is a Object containing info/data about Tunnel. It has following useful attributes/methods:

  • isHttps - Is session encrypted.
  • getTunnelStats() - Get Stats for this tunnel
  • getId() - Get Own ID-Session
  • isAuthenticated() - Is the session authenticated by user or not.

.getBridgedConnections()

const ProxyServer = require('transparent-proxy');
const server = new ProxyServer();

//starting server on port 8080
server.listen(8080, '0.0.0.0', function () {
    console.log('Proxy-Server started!', server.address());
});

setInterval(function showOpenSockets() {
    const bridgedConnections = server.getBridgedConnections();
    console.log([new Date()], 'OPEN =>', Object.keys(bridgedConnections).length)
}, 2000);

Examples

This example upstreams only requests for ifconfig.me to another proxy, for all other requests will be used localhost.

const ProxyServer = require('transparent-proxy');

const server = new ProxyServer({
    upstream: function (data, session) {
        if (~(data.toString().indexOf('ifconfig.me'))) {
            return 'x.x.x.x:3128'; // upstream to other proxy
        } else {
            return 'localhost'; //upstream to localhost
        }
    },
});

//starting server on port 8080
server.listen(8080, '0.0.0.0', function () {
    console.log('TCP-Proxy-Server started!', server.address());
});

Testing with curl:

curl -x 127.0.0.1:8080 https://ifconfig.me
x.x.x.x

curl -x 127.0.0.1:8080 https://ifconfig.co
y.y.y.y

For more examples look here.