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Jan
14

Self-signed certs with secure WebSockets in Node.js

Category: Development, JavaScript, Node.js Tags: JavaScript, ssl, websockets 2 Comments

First generate your self-signed certs:

    openssl req -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem -days 100 -nodes

1	openssl req -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem -days 100 -nodes

Then create your httpsServer from an express app using node’s built-in https server:

    var privateKey  = fs.readFileSync('sslcert/key.pem', 'utf8');
    var certificate = fs.readFileSync('sslcert/cert.pem', 'utf8');

    var credentials = {key: privateKey, cert: certificate};
    var express = require('express');
    var app = express();

    //... bunch of other express stuff here ...

    //pass in your express app and credentials to create an https server
    var httpsServer = https.createServer(credentials, app);
    httpsServer.listen(8443);

var privateKey = fs.readFileSync('sslcert/key.pem', 'utf8');

var certificate = fs.readFileSync('sslcert/cert.pem', 'utf8');

var credentials = {key: privateKey, cert: certificate};

var express = require('express');

var app = express();

//... bunch of other express stuff here ...

//pass in your express app and credentials to create an https server

var httpsServer = https.createServer(credentials, app);

httpsServer.listen(8443);

Then setup your websocket server (ironically this will use the same port as the http server, I didn’t know this but I guess protocols can share ports? — this had me going for awhile).

    var WebSocketServer = require('ws').Server;
    var wss = new WebSocketServer({
        server: httpsServer
      });

    wss.on('connection', function connection(ws) {
      ws.on('message', function incoming(message) {
        console.log('received: %s', message);
      });

      ws.send('something');
    });

var WebSocketServer = require('ws').Server;

var wss = new WebSocketServer({

server: httpsServer

});

wss.on('connection', function connection(ws) {

ws.on('message', function incoming(message) {

console.log('received: %s', message);

});

ws.send('something');

});

Now browse to https://0.0.0.0:8443 server and accept the self-signed cert in Chrome. Then websockets should now work isnide the browser.

Open a chrome devtools console and type:

    var ws = new WebSocket('wss://0.0.0.0:8443');
    ws.send('foo');

1 2	var ws = new WebSocket('wss://0.0.0.0:8443'); ws.send('foo');

This is a preview of Self-signed certs with secure WebSockets in Node.js. Read the full post (146 words, estimated 35 secs reading time)

Dec
17

By chovy

Fibonacci generator using EcmaScript 6 (es6)

Category: JavaScript, Node.js 1 Comment

I took my first stab at the --harmony flag on node 11 to play with generators.

Thanks to this video:

Here’s a simple example of using an ES6 generator to generate the first 10 numbers in the Fibonnaci sequence:

#!/usr/bin/env node --harmony

'use strict';

var fib = getFibonacci();

init();

function* getFibonacci(){
  let val1 = 0, val2 = 1, swap;

  yield val1;
  yield val2;

  while (true){
    swap = val1 + val2;
    val1 = val2;
    val2 = swap;

    yield swap;
  }
}

function init(){
  let i = 0;

  while ( i < 10 ) {
    console.log(fib.next().value);
    i++;
  }
}

#!/usr/bin/env node --harmony

'use strict';

var fib = getFibonacci();

init();

function* getFibonacci(){

let val1 = 0, val2 = 1, swap;

yield val1;

yield val2;

while (true){

swap = val1 + val2;

val1 = val2;

val2 = swap;

yield swap;

}

function init(){

let i = 0;

while ( i < 10 ) {

console.log(fib.next().value);

i++;

}

What wasn’t clear to me before watching this video by Netflix UI Architect Jafar Husain was that a generator returns an “iterator”….and on that iterator you call “.next()” to get the next yield. A generator can yield infinite times, so in this case we loop over the fib.next() call 10 times to get the first 10 numbers.

This is a preview of Fibonacci generator using EcmaScript 6 (es6). Read the full post (191 words, estimated 46 secs reading time)

Dec
16

By chovy

A gentle introduction to bitcoin

Category: Bitcoin Leave a Comment

I recently (2 years ago) discovered Bitcoin and started researching and following it back then. The price was about $14 when I seriously considered buying some. The technology posed a bit of a hurdle in the learning curve, so here are a few thoughts on how to go about buying bitcoins, managing wallets, and spending your BTC.

First, I live in the USA. So transferring money from a bank account is pretty well supported on popular money sites (PayPal, Dwolla, Coinbase).

If you live outside the US, try a site like LocalBitcoins.com which has many ways to buy and sell Bitcoins person-to-person.

This is a preview of A gentle introduction to bitcoin. Read the full post (353 words, estimated 1:25 mins reading time)

May
16

By chovy

Example of $resource in Angular.js with update and save using a resolver.

Category: JavaScript Leave a Comment

I had some issues trying to understand how to use a resolver (for edit view) and $resource to do both a POST (save) and a PUT (update) method call to an API.

Here is an example plurk: http://plnkr.co/edit/KQR1EZPqW0MjLTorCmMr?p=preview

Here is the route, the edit path uses a resolver to pass ‘thing’ object/promise back to the edit.html view before the page loads — this is to prepopulate the form:

angular.module('ThingApp', [
    'ngCookies',
    'ngResource',
    'ngSanitize',
	  'btford.markdown',
    'ngRoute'
])
    .config(function ($routeProvider, $locationProvider, $httpProvider) {
        $routeProvider
          .when('/things', {
            templateUrl: 'partials/things/index',
            controller: 'ThingsCtrl'
          })
          .when('/things/new', {
          	templateUrl: 'partials/things/new',
            	controller: 'ThingCtrl',
			        authenticate: true
          })
    			.when('/things/edit/:id', {
    				templateUrl: 'partials/things/edit',
    				controller: 'ThingEditCtrl',
    				authenticate: true,
    				resolve: {
    				  //this gets passed as 'thing' to edit controller
    				  //we can now use full promise interface and as the model
    					thing: ['$route', 'Thing', function($route, Thing){
    						return Thing.get({ id: $route.current.params.id});
    					}]
    				}
    			})
          .otherwise({
              redirectTo: '/'
          });

    });

angular.module('ThingApp', [

'ngCookies',

'ngResource',

'ngSanitize',

'btford.markdown',

'ngRoute'

])

.config(function ($routeProvider, $locationProvider, $httpProvider) {

$routeProvider

.when('/things', {

templateUrl: 'partials/things/index',

controller: 'ThingsCtrl'

})

.when('/things/new', {

templateUrl: 'partials/things/new',

controller: 'ThingCtrl',

authenticate: true

})

.when('/things/edit/:id', {

templateUrl: 'partials/things/edit',

controller: 'ThingEditCtrl',

authenticate: true,

resolve: {

//this gets passed as 'thing' to edit controller

//we can now use full promise interface and as the model

thing: ['$route', 'Thing', function($route, Thing){

return Thing.get({ id: $route.current.params.id});

}]

}

})

.otherwise({

redirectTo: '/'

});

This is a preview of Example of $resource in Angular.js with update and save using a resolver.. Read the full post (269 words, estimated 1:05 mins reading time)

Nov
10

By chovy

Setup email forwarding with Postfix on Debian

Category: Linux 2 Comments

As you are probably aware, setting up a fully functional email server is a daunting task to say the least.

On my dedicated server I wanted to have simple email forwarding for email aliases on my domain. For example help@example.com would forward to my Gmail account. I didn’t want to jump through the hoops to setup a fully functional SMTP/Inbox/Imap email server when all I needed was a forwarding address at my custom domain.

Here are the steps, which takes around 10 minutes.

# install postfix

	apt-get install postfix
	# choose "No Configuration" when prompted
	cp /usr/share/postfix/main.cf.debian /etc/postfix/main.cf

# setup alias map

	vi /etc/postfix/main.cf

	# add these lines
	virtual_alias_domains = example.com example2.com #and other domains space separated
	virtual_alias_maps = hash:/etc/postfix/virtual

# setup DNS records:

	example.com.	1800	MX	Pref: 0; Exchange: mx.example.com.
	mx.example.com.	1800	A	x.x.x.x (your server's public ip)

# add forwarding

	vi /etc/postfix/virtual
	help@example.com you@gmail.com
	help@example2.com someone@gmail.com

# Uncomment submission line (port 587) below the smtp line to listen on port 587:

	vi /etc/postfix/master.cf
	smtp      inet  n       -       -       -       -       smtpd
	submission inet n       -       -       -       -       smtpd

# open up port 587 in firewall (see iptables.md for setup)

	vi /etc/iptables

	# Allow mx connections
	-A INPUT -p tcp --dport 25 -j ACCEPT
	-A INPUT -p tcp --dport 587 -j ACCEPT

# start postfix and update virtual map

	/etc/init.d/postfix start
	postmap /etc/postfix/virtual
	postfix reload

# check logs

	tail -f /var/log/mail.*

# install postfix

apt-get install postfix

# choose "No Configuration" when prompted

cp /usr/share/postfix/main.cf.debian /etc/postfix/main.cf

# setup alias map

vi /etc/postfix/main.cf

# add these lines

virtual_alias_domains = example.com example2.com #and other domains space separated

virtual_alias_maps = hash:/etc/postfix/virtual

# setup DNS records:

example.com. 1800 MX Pref: 0; Exchange: mx.example.com.

mx.example.com. 1800 A x.x.x.x (your server's public ip)

# add forwarding

vi /etc/postfix/virtual

help@example.com you@gmail.com

help@example2.com someone@gmail.com

# Uncomment submission line (port 587) below the smtp line to listen on port 587:

vi /etc/postfix/master.cf

smtp inet n - - - - smtpd

submission inet n - - - - smtpd

# open up port 587 in firewall (see iptables.md for setup)

vi /etc/iptables

# Allow mx connections

-A INPUT -p tcp --dport 25 -j ACCEPT

-A INPUT -p tcp --dport 587 -j ACCEPT

# start postfix and update virtual map

/etc/init.d/postfix start

postmap /etc/postfix/virtual

postfix reload

# check logs

tail -f /var/log/mail.*

More info can be found here: http://www.postfix.org/VIRTUAL_README.html#forwarding

Permanent link to this post (118 words, estimated 28 secs reading time)

Chovy's Blog

Self-signed certs with secure WebSockets in Node.js

Fibonacci generator using EcmaScript 6 (es6)

A gentle introduction to bitcoin

Example of $resource in Angular.js with update and save using a resolver.

Setup email forwarding with Postfix on Debian

Tip me in Bitcoin

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