use Net::LDAP;

## Fill in the following as you would sitting down in a chair and logging in with standard Windows ActiveDirectory credentials..

$userName="YOURDOMAIN\\YourADAccountNameHere";
$pw="whateverpasswordyouhave";

## BTW, if you're getting these variables passed to you via a webpage, it's important to convert special characters that have been translated into their Unicode equivalents back to straight ASCII. (For example, if your password has a ! in it, it's going to get passed as "%21" (or whatever)).. So, to fix that, we repack the string with some sweet, sweet regex lovin'. If not, the following two lines should be omitted.

$pw=~s/\%([A-Fa-f0-9]{2})/pack('C',hex($1))/seg;
$pw=~s/\+/ /g;

## On with the show..

$host="123.123.123.123";
$ldap=Net::LDAP->new($host) or die "Can't connect to LDAP server: $@";
$mesg=$ldap->bind($userName, password=>$pw);
$results=sprintf("%s",$mesg->error);
$mesg=$ldap->unbind;

if ($results=~/Success/)
{
   print "Thank you. You have successfully authenticated; You may now enter picturesofcatslookingatofficeequipment.com";
}
else
{
   print "You are a horrible, horrible person, and a slut. Try again.";
}