נסה את זה:
קוד:
Options +FollowSymlinks
RewriteEngine on
rewritecond %{http_host} ^site.com$ [nc]
rewriterule ^(.*)$ http://www.site.com/$1 [r=301,nc]
rewritecond %{http_host} ^site.com/forum [nc]
rewriterule ^(.*)$ http://forum.site.com/$1 [r=301,nc]