Specifically, how do I gain access into an Apache (Ubuntu) server? There are forms yet they don't allow SQL injection (only know from what I have specifically attempted, maybe I'm missing something). These forms DO connect to a SQL database and the login forms are unencrypted (don't use SSL). Is there any general thing that I should try? The only open ports are the classic SSH, FTP, HTTP, and MS-DS (filtered).
EDIT: Entering certain things after such as "%3C" lead to a blank page, and changing "?" to "/" lead to the page still loading, but broken (not loading CSS and such)