TCP socket client through proxy on nodejs

Question

I need to make tcp socket connection to smtp server. Is it possible to connect through proxy server on nodejs? Is there any npm modules available to use? I couldn't find any at all.

var net = require('net');

var HOST = '127.0.0.1';
var PORT = 6969;

var client = new net.Socket();
client.connect(PORT, HOST, function() {
    console.log('CONNECTED TO: ' + HOST + ':' + PORT);
    client.write('I am here!');
});

// Add a 'data' event handler for the client socket
// data is what the server sent to this socket
client.on('data', function(data) {

    console.log('DATA: ' + data);

});

// Add a 'close' event handler for the client socket
client.on('close', function() {
    console.log('Connection closed');
});

Answer 1

net.socket , tls.connect and dgram have no proxy support.

The simplest way to use it with proxy is to replace some libc functions with proxychains or something similar.

var client = require('tls')
.connect(443, 'www.facebook.com', function() {
  console.log('connected');
  client.write('hello');
})
.on('data', function(data) {
  console.log('received', data.toString());
})
.on('close', function() {
  console.log('closed');
});

proxychains node fit.js

connected
received HTTP/1.1 400 Bad Request
...
closed

Answer 2

Yes, it is possible with one of these NPM modules:

http-proxy-agent : An HTTP(s) proxy http.Agent implementation for HTTP endpoints

https-proxy-agent : An HTTP(s) proxy http.Agent implementation for HTTPS endpoints

pac-proxy-agent : A PAC file proxy http.Agent implementation for HTTP and HTTPS

socks-proxy-agent : A SOCKS (v4a) proxy http.Agent implementation for HTTP and HTTPS

HTTPS Proxy Example:

var url = require('url');
var WebSocket = require('ws');
var HttpsProxyAgent = require('https-proxy-agent');

// HTTP/HTTPS proxy to connect to
var proxy = process.env.http_proxy || 'http://168.63.76.32:3128';
console.log('using proxy server %j', proxy);

// WebSocket endpoint for the proxy to connect to
var endpoint = process.argv[2] || 'ws://echo.websocket.org';
var parsed = url.parse(endpoint);
console.log('attempting to connect to WebSocket %j', endpoint);

// create an instance of the `HttpsProxyAgent` class with the proxy server information
var opts = url.parse(proxy);

var agent = new HttpsProxyAgent(opts);

// finally, initiate the WebSocket connection
var socket = new WebSocket(endpoint, { agent: agent });

socket.on('open', function () {
  console.log('"open" event!');
  socket.send('hello world');
});

socket.on('message', function (data, flags) {
  console.log('"message" event! %j %j', data, flags);
  socket.close();
});

I hope this helps.

Answer 3

Other than 'net' you don't need another module to make a socket connect to a host through a proxy server as long at the proxy server supports HTTPS traffic.

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   Even though this process starts with HTTP it doesn't mean it wouldn't work for SMTP traffic. The initial HTTP message is just used to negotiate the connection, after that its just raw traffic. A proxy server might look at the port or host you want to connect to and disallow it. For example, block connections to ports below 80 or below 443 such as port 25 so it really depends on the proxy server if the connection will be allowed.

   "