This is one of the problems with installing SMF or any other script in the default (public_html) directory. You certainly do NOT want to redirect index.php as it will cause SMF to quit working. Instead your best bet (short of moving the SMF install to a different directory)
I agree 100%. Never install anything other than the site control files (.htaccess, robots.txt, error documents, favicon.ico) and possibly your Home Page into
public_html/. Put major subsystems into their own subdirectories (e.g.,
public_html/forum/ to hold SMF). If you don't want to move SMF to a lower level,
is to add the following to your .htaccess file:
DirectoryIndex directory.php
will work. Instead of looking for index.html, then index.htm, and finally index.php, the server will look only for directory.php. That could cause problems down the road, so I would extend the llist:
DirectoryIndex directory.php index.html index.htm index.php
This will keep things as before, except for looking for "directory.php" first.