app.post('/auth',urlencodedParser,function (req, res) {

    conn.query('SELECT * FROM users WHERE user_name="'+req.body.username+'" AND user_pass="'+req.body.password+'"',function(err,res1){
        if(err) {
            console.log("Error!");
            res.send('-2');
        }
        else{
            if(res1.length==0) {
                console.log("No matching!");
                res.send('-2');
            }
            else if(res1.length==1){
                req.session.username = req.body.username; //This is my session variable
                console.log("Successful login with: " + req.session.username); //This works fine
                res.send('1');
            }
        }
    });
});

app.post('/privilage',urlencodedParser,function (req, res) {

console.log("privilage: " + req.session.username);  //Here is where I need to check and it says "undefined"

    if(!req.session.username){
        res.send('-2');
    }
    else res.send('1');
});