user authentication libraries for node.js?

If you are looking for an authentication framework for Connect or Express, Passport is worth investigating: https://github.com/jaredhanson/passport

(Disclosure: I'm the developer of Passport)

I developed Passport after investigating both connect-auth and everyauth. While they are both great modules, they didn't suit my needs. I wanted something that was more light-weight and unobtrusive.

Passport is broken down into separate modules, so you can choose to use only what you need (OAuth, only if necessary). Passport also does not mount any routes in your application, giving you the flexibility to decide when and where you want authentication, and hooks to control what happens when authentication succeeds or fails.

For example, here is the two-step process to setup form-based (username and password) authentication:

passport.use(new LocalStrategy(
  function(username, password, done) {
    // Find the user from your DB (MongoDB, CouchDB, other...)
    User.findOne({ username: username, password: password }, function (err, user) {
      done(err, user);
    });
  }
));

app.post('/login', 
  passport.authenticate('local', { failureRedirect: '/login' }),
  function(req, res) {
    // Authentication successful. Redirect home.
    res.redirect('/');
  });

Additional strategies are available for authentication via Facebook, Twitter, etc. Custom strategies can be plugged-in, if necessary.

Session + If

I guess the reason that you haven't found many good libraries is that using a library for authentication is mostly over engineered.

What you are looking for is just a session-binder :) A session with:

if login and user == xxx and pwd == xxx 
   then store an authenticated=true into the session 
if logout destroy session

thats it.

---

I disagree with your conclusion that the connect-auth plugin is the way to go.

I'm using also connect but I do not use connect-auth for two reasons:

1. IMHO breaks connect-auth the very powerful and easy to read onion-ring architecture of connect. A no-go - my opinion :). You can find a very good and short article about how connect works and the onion ring idea here.

2. If you - as written - just want to use a basic or http login with database or file. Connect-auth is way too big. It's more for stuff like OAuth 1.0, OAuth 2.0 & Co

---

A very simple authentication with connect

(It's complete. Just execute it for testing but if you want to use it in production, make sure to use https) (And to be REST-Principle-Compliant you should use a POST-Request instead of a GET-Request b/c you change a state :)

var connect = require('connect');
var urlparser = require('url');

var authCheck = function (req, res, next) {
    url = req.urlp = urlparser.parse(req.url, true);

    // ####
    // Logout
    if ( url.pathname == "/logout" ) {
      req.session.destroy();
    }

    // ####
    // Is User already validated?
    if (req.session && req.session.auth == true) {
      next(); // stop here and pass to the next onion ring of connect
      return;
    }

    // ########
    // Auth - Replace this example with your Database, Auth-File or other things
    // If Database, you need a Async callback...
    if ( url.pathname == "/login" && 
         url.query.name == "max" && 
         url.query.pwd == "herewego"  ) {
      req.session.auth = true;
      next();
      return;
    }

    // ####
    // This user is not authorized. Stop talking to him.
    res.writeHead(403);
    res.end('Sorry you are not authorized.\n\nFor a login use: /login?name=max&pwd=herewego');
    return;
}

var helloWorldContent = function (req, res, next) {
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.end('authorized. Walk around :) or use /logout to leave\n\nYou are currently at '+req.urlp.pathname);
}

var server = connect.createServer(
      connect.logger({ format: ':method :url' }),
      connect.cookieParser(),
      connect.session({ secret: 'foobar' }),
      connect.bodyParser(),
      authCheck,
      helloWorldContent
);

server.listen(3000);

NOTE

I wrote this statement over a year ago and have currently no active node projects. So there are may be API-Changes in Express. Please add a comment if I should change anything.