PHP - Security what is best way?

Question

What is the best way to secure an intranet website developed using PHP from outside attacks?

Answer 1

The best way? Disable direct external access!

If employees need to use it (like an extranet-style site), you should make them VPN in. Through VPN you have a lot more authentication options and most of them are a great deal more secure than leaving your intranet server accessible from the internet.

Another option, and this only works if the data is public-safe, is scheduling your intranet server to push the data to another server that is externally accessible. I say push because you really don't want this server to have access to your network. Let your network server do the work.