Help Little Bill Blue Hill. Will you, ... please?
Bill has writen a cool php+mysql app called ass_saver. He has humbly placed a 5 figure price tag on it - 'all cool things in life, have a five figure price tag on them'. Ass_saver is intended to work on a LAN
This is what he plans to do to save HIS ass so to speak:
1. On each client's server he installs Linux, then Apache, then MySQL, then php, and finally ass_saver.
Note: He does not give anyone any source code or installer or anything - he just plain installs everything himself.
2. He chooses the most restrictive file/directory/database access permissions so that nothing is accessible from the console. ass_saver can only be accessed as served dynamic html pages requested from the machines on the LAN.
Question 1: How do you acheive this much restriction? chmod what? root?
3. After he is done he turns the server to the client and leaves with his check. But that same night he has a nightmare. In his nightmare he sees the client is not using ass_saver, but abusing Bills ass. How? They have taken the hard disk out of the server's case and have made it slave to the primary on a w*dos machine and are diskcopying it to other hard disks. Within a few days they make hundreds of duplicates. and start selling them at one-tenth of Bills price.
Question 2: Could that happen outside the fuzzy world of dreams?
4. Latter in his dream Bill is sitting in his office looking at his goldfish when his cell phone rings. It's the customer. He proposes a deal:
'As you know, we cannot change the company name and logo, but at one-tenth of your price we can find hundreds of clients who will be willing to buy ass_saver even with our company name and logo on them. And for your information our chief programmer has written a cool Grease Monkey script to replace the name and logo without any effort from the client'
'So, go and do that bastard. Why have you called me then?'
'Because sooner or latter one of our clients will be as smart as our self and make duplicates and sell them for three figure sums, ... or worse, ... you might go mad and publish the source and give birth to what might be called open source movement.'
'And how is all that going to change?'
'We can change the source so that the duplicates do not work.'
'How?'
Question 3-5: [3]Which options below work and which don't? - [4]Why? - [5]How?
Option 1 - Use serial number of the hard disk
Option 2 - Use a hardware lock connected to the server's serial or parallel port
Option 3 - Use the NIC address of the network card present on the server
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I (Bill's agent), thank you for any suggestions.

For Securing Application:
1. Encrypt/Encode the php code of ass_saver with ioncube [Php encoder] like applications.
2. Generate Serial key based on any uniq parameter like MAC adderess.
3. Add some checks for serial key in Encrypted/Encoded code.

If ass_saver is an online application, then add code for checking authenticity from Centralized database on Bill's online server.