Someone is trying very hard to install perlbot on this server, and he's using a real old exploit in phpbb. This is installed, but not active, so all attempts ( GET /modules/Forums/admin/admin_board.php?phpbb_root_path= HTTP/1.1" 200 9746 "-" "libwww-perl/5.65" ) just fail, but the CMS keeps gently denying access.

11 attempts at nov-8
63 attempts at nov-9
112 attempts at nov-10, they appear 6 times per hour.

Al attempts from different ip-addresses, as far as I can tell they are compromised PHP-Nuke's: