Okay, I tried...
my .htaccess in folder phpBB3 looks like:
RewriteEngine On
RewriteBase /forum
RewriteCond %{REQUEST_FILENAME} /phpBB3(\/?)$
RewriteRule (.*) /forum [R=301,L]
RewriteCond %{REQUEST_FILENAME} /phpBB3/index.php
RewriteRule (.*) /forum?%{QUERY_STRING} [R=301,L]
RewriteCond %{REQUEST_FILENAME} /phpBB3/ucp.php
RewriteRule (.*) /forum/user?%{QUERY_STRING} [R=301,L]
RewriteCond %{REQUEST_FILENAME} /phpBB3/viewforum.php
RewriteRule (.*) /forum/forum?%{QUERY_STRING} [R=301,L]
RewriteCond %{REQUEST_FILENAME} /phpBB3/viewtopic.php
RewriteRule (.*) /forum/topic?%{QUERY_STRING} [R=301,L]
RewriteCond %{REQUEST_FILENAME} /phpBB3/memberlist.php
RewriteRule (.*) /forum/members?%{QUERY_STRING} [R=301,L]
RewriteCond %{REQUEST_FILENAME} /phpBB3/report.php
RewriteRule (.*) /forum/report?%{QUERY_STRING} [R=301,L]
RewriteCond %{REQUEST_FILENAME} /phpBB3/posting.php
RewriteRule (.*) /forum/post?%{QUERY_STRING} [R=301,L]
RewriteCond %{REQUEST_FILENAME} /phpBB3/mcp.php
RewriteRule (.*) /forum/moderator?%{QUERY_STRING} [R=301,L]
And my .htaccess in / folder looks like:
##### RewriteEngine enabled - BEGIN
RewriteEngine On
##### RewriteEngine enabled - END
##### RewriteBase set - BEGIN
RewriteBase /
##### RewriteBase set - END
##### File execution order -- BEGIN
DirectoryIndex index.php index.html
##### File execution order -- END
##### No directory listings -- BEGIN
IndexIgnore *
Options All -Indexes
##### No directory listings -- END
##### Common hacking tools and bandwidth hoggers block -- BEGIN
SetEnvIf user-agent "Indy Library" stayout=1
SetEnvIf user-agent "libwww-perl" stayout=1
SetEnvIf user-agent "Download Demon" stayout=1
SetEnvIf user-agent "GetRight" stayout=1
SetEnvIf user-agent "GetWeb!" stayout=1
SetEnvIf user-agent "Go!Zilla" stayout=1
SetEnvIf user-agent "Go-Ahead-Got-It" stayout=1
SetEnvIf user-agent "GrabNet" stayout=1
SetEnvIf user-agent "TurnitinBot" stayout=1
deny from env=stayout
##### Common hacking tools and bandwidth hoggers block -- END
##### Redirect index.php to / -- BEGIN
RewriteCond %{THE_REQUEST} !^POST
RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /index\.php\ HTTP/
RewriteCond %{SERVER_PORT}>s ^(443>(s)|[0-9]+>s)$
RewriteRule ^index\.php$ http%2://www.burn-out-forum.de/ [R,L]
##### Redirect index.php to / -- END
##### Redirect non-www to www -- BEGIN
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [R,L]
##### Redirect non-www to www -- END
##### Rewrite rules to block out some common exploits -- BEGIN
RewriteCond %{QUERY_STRING} proc/self/environ [OR]
RewriteCond %{QUERY_STRING} mosConfig_[a-zA-Z_]{1,21}(=|\%3D) [OR]
RewriteCond %{QUERY_STRING} base64_(en|de)code\(.*\) [OR]
RewriteCond %{QUERY_STRING} (<|%3C).*script.*(>|%3E) [NC,OR]
RewriteCond %{QUERY_STRING} GLOBALS(=|\[|\%[0-9A-Z]{0,2}) [OR]
RewriteCond %{QUERY_STRING} _REQUEST(=|\[|\%[0-9A-Z]{0,2})
RewriteRule .* index.php [F]
##### Rewrite rules to block out some common exploits -- END
##### File injection protection -- BEGIN
RewriteCond %{REQUEST_METHOD} GET
RewriteCond %{QUERY_STRING} [a-zA-Z0-9_]=http:// [OR]
RewriteCond %{QUERY_STRING} [a-zA-Z0-9_]=(\.\.//?)+ [OR]
RewriteCond %{QUERY_STRING} [a-zA-Z0-9_]=/([a-z0-9_.]//?)+ [NC]
RewriteRule .* - [F]
##### File injection protection -- END
##### Advanced server protection rules exceptions -- BEGIN
RewriteRule ^administrator\/components\/com_akeeba\/restore\.php$ - [L]
RewriteRule ^administrator\/components\/com_admintools\/restore\.php$ - [L]
RewriteRule ^administrator\/components\/com_joomlaupdate\/restore\.php$ - [L]
RewriteRule ^templates\/jsn_epic_pro/ - [L]
RewriteRule ^phpBB3/ - [L]
RewriteRule ^forum/ - [L]
##### Advanced server protection rules exceptions -- END
##### Advanced server protection -- BEGIN
RewriteCond %{QUERY_STRING} \=PHP[a-f0-9]{8}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{12} [NC]
RewriteRule .* - [F]
## Back-end protection
RewriteRule ^administrator/?$ - [L]
RewriteRule ^administrator/index\.(php|html?)$ - [L]
RewriteRule ^administrator/index[23]\.php$ - [L]
RewriteRule ^administrator/(components|modules|templates|images|plugins)/.*\.(jpe|jpg|jpeg|jp2|jpe2|png|gif|bmp|css|js|swf|html|mpg|mp3|mpeg|mp4|avi|wav|ogg|ogv|xls|xlsx|doc|docx|ppt|pptx|zip|rar|pdf|xps|txt|7z|svg|odt|ods|odp|flv|mov|htm|ttf|woff|eot)$ - [L]
RewriteRule ^administrator/ - [F]
## Allow limited access for certain Joomla! system directories with client-accessible content
RewriteRule ^(components|modules|templates|images|plugins|media|libraries|media/jui/fonts)/.*\.(jpe|jpg|jpeg|jp2|jpe2|png|gif|bmp|css|js|swf|html|mpg|mp3|mpeg|mp4|avi|wav|ogg|ogv|xls|xlsx|doc|docx|ppt|pptx|zip|rar|pdf|xps|txt|7z|svg|odt|ods|odp|flv|mov|ico|htm|ttf|woff|eot)$ - [L]
RewriteRule ^(components|modules|templates|images|plugins|media|libraries|media/jui/fonts)/ - [F]
## Disallow front-end access for certain Joomla! system directories (unless access to their files is allowed above)
RewriteRule ^includes/js/ - [L]
RewriteRule ^(cache|includes|language|logs|tmp)/ - [F]
RewriteRule ^(configuration\.php|CONTRIBUTING\.md|htaccess\.txt|joomla\.xml|LICENSE\.txt|phpunit\.xml|README\.txt|web\.config\.txt) - [F]
## Disallow access to rogue PHP files throughout the site, unless they are explicitly allowed
RewriteCond %{REQUEST_FILENAME} (\.php)$
RewriteCond %{REQUEST_FILENAME} !(/index[23]?\.php)$
RewriteCond %{REQUEST_FILENAME} -f
RewriteRule (.*\.php)$ - [F]
## Disallow access to htaccess.txt, php.ini and configuration.php-dist
RewriteRule ^(htaccess\.txt|configuration\.php-dist|php\.ini)$ - [F]
##### Advanced server protection -- END
##### Joomla! core SEF Section -- BEGIN
RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]
RewriteCond %{REQUEST_URI} !^/index\.php
RewriteCond %{REQUEST_URI} /component/|(/[^.]*|\.(php|html?|feed|pdf|raw|ini|zip|json|file|vcf))$ [NC]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule .* index.php [L]
##### Joomla! core SEF Section -- END
Effect: every link is broken. Only forum-index will work. When deleting "forum/" from exceptions, all links work, but not the links with ".php" inside.
The real folder for the board is "forum", not forums. I always considered this. In my first question I postet the standard-rules.
Regards
Samson
