Why is Node.js app accessible only from 127.0.0.1/localhost?

Question

I was about teaching my friend an intro to node but then I wonder why this code from nodejs.org:

var http = require('http');
http.createServer(function (req, res) {
    res.writeHead(200, {'Content-Type': 'text/plain'});
    res.end('Hello World\n');
}).listen(80, '127.0.0.1');
console.log('Server running at http://127.0.0.1:80/');

when hosted, it doesn't accessible from public ip (it's still accessible from localhost though) while this code from express.js:

var express = require('express');
var routes = require('./routes');
var user = require('./routes/user');
var http = require('http');
var path = require('path');

var app = express();

// all environments
app.set('port', process.env.PORT || 80);
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'jade');
app.use(express.favicon());
app.use(express.logger('dev'));
app.use(express.json());
app.use(express.urlencoded());
app.use(express.methodOverride());
app.use(app.router);
app.use(express.static(path.join(__dirname, 'public')));

// development only
if ('development' == app.get('env')) {
  app.use(express.errorHandler());
}

app.get('/', routes.index);
app.get('/users', user.list);

http.createServer(app).listen(app.get('port'), function(){
  console.log('Express server listening on port ' + app.get('port'));
});

does. Please help me modify the basic code the one from nodejs's homepage so that it become accessible from public ip so I can demonstrate it to my friend in a very basic way. The fresh code generated by express.js worked just fine.

What am I missing here?

Answer 1

As per the server.listen docs,

Begin accepting connections on the specified port and hostname. If the hostname is omitted, the server will accept connections directed to any IPv4 address (INADDR_ANY).

To make it accept connections from all ips (0.0.0.0), change it to read like this

}).listen(80); // No explicit ip, defaults to all ips 0.0.0.0
console.log('Server running in port 80');