I'm learning Java, PHP, HTML, xml, ajax and other web and Linux related stuff.
Once every while I find someone giving me cryptic and scary warnings about security, say: "...if connected to Internet don't install php if you don't know what you are doing..."
So far I can't claim that I know what I'm doing.
So... what should I study in order to obtain a sufficiently deep and practical understanding about how to develop a formally secure server and/or Internet exposed Linux system?
(I say "formally secure" because I understand that ultimately any system has security vulnerabilities.)
Is there a bible like book? or a list of recommended topics?
What are the most important considerations?
What technique or method (if any) is the best to test the security of a server?