Options +FollowSymLinks
IndexIgnore */*
RewriteEngine on
RewriteRule ^blog/(.*)$ /posts/$1 [R=301,L]
# if a directory or a file exists, use it directly
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
# otherwise forward it to index.php
RewriteRule ^(.*)$ index.php [QSA,L]