[SOLVED] Login script help, sessions won't last

[Tandem]

Hey guys,

 

It's been a while since I got off my butt and wrote some php so i'm a bit rusty.

 

I'm writing a login script. At first it appears to work fine, if you put in the right username/pw then you get up a little admin panel. But when I click any of the links for my admin-only pages, I get logged out right away. Each of the admin-only pages has a little included script which checks to make sure I have a session going, and taking me back to the login page if I haven't.

 

So basically my problem is that my sessions appear to be only lasting for one page load, and I want them to last long enough to at least view another page

 

Here's the login script:

<?php
include 'db.php';
if ((isset($_POST['submit'])) && (!isset($_SESSION['username']))) {  		 //if form is submitted and you aren't already logged in
if (ctype_alnum($_POST['username'])) {                           		//check the username is alphanumeric
	$_POST['password'] = md5($_POST['password']);			   //convert the password to an md5 hash
	$query = mysql_query("select username from login where username='$_POST[username]' and password='$_POST[password]'");
	if (mysql_num_rows($query)>0) {
		session_start();
		$_SESSION['username'] = mysql_result($query, 0);
	}
	else {
		$success = false;	
	}
}
else {
	$success = false;	
}
}
include 'top.php';
if ((isset($_POST['submit'])) && (isset($success))) {
echo '<div id="error">Wrong Username/Password.</div>';
}
?>
<div id="tcontent"></div>
<div id="content">

<?php
if (!isset($_SESSION['username'])) { 
?>
<form action="login.php" method="POST">
<center>
Username: <input type="text" name="username" /><br />
Password: <input type = "password" name="password" /><br />
<input type="submit" name="submit" value="Submit!" />
</center>
</form>

<?php
}
else {
include 'adminlinks.php';	
}
?>
</div>
<div id="bcontent"></div>
<?php
include 'bottom.php';
?>

 

and the session check in case i've made an embarrassingly obvious mistake that only I can't see, is:

<?php
if (!isset($_SESSION['username'])) {
header("Location: login.php");         //back to the login page
}
?>

 

Also in case it helps, my hard drive died not too long ago taking with it my apache/php installation, and this new installation is relatively untouched so i may need to mess with the conifgurations if it's not the code.

 

Thanks guys.

[peranha]

you need session_start() at the top of every page that you are checking sessions on.

 

<?php

session_start();

 

if (!isset($_SESSION['username'])) {

header("Location: login.php");        //back to the login page

}

?>

[Tandem]

Thanks man. I've just read through 3 tutorials that are all entirely wrong then

 

Much appreciated.

[DarkWater]

Some tutorials are absolutely horrible, and some are completely amazing.