1x1.js

var http = require('http');
var fs = require('fs');
var img = fs.readFileSync('1x1.gif');

var server = http.createServer(function (req, res) {
	res.writeHead(200, {'Content-Type': 'image/gif' });
	res.end(img, 'binary');
});

var port = 3000;
server.listen(port, '0.0.0.0', function() {
	console.log('Started on port ' + port);
});