gistfile1.txt

% curl http://localhost:8000/ > outf
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 1024M  100 1024M    0     0  20.2M      0  0:00:50  0:00:50 --:--:-- 19.8M
%

test.js

// dd if=/dev/zero of=bigfile bs=1024 count=1048576
var http = require('http');
var fs = require('fs');

var stat = fs.statSync('bigfile');
console.log(stat);

var s = http.Server(function(req, res) {
  res.writeHead(200, {
    'Content-Length': stat.size
  });
  fs.ReadStream('bigfile').pipe(res);
});

s.listen(8000);