How to block access to a sub-site with mod_rewrite?

Question

Let's say I have the sites siteA.com and siteB.com. They are hosted such that siteB.com actually points to siteA.com/siteB.

How can I block someone from visiting siteA.com/siteB using mod_rewrite?

So far I've tried this to no avail (in root of siteA.com):

RedirectMatch 301 ^/siteB/$ http://someothersite.com/

Answer 1

Try something like

# you may need to drop the leading slash if you're doing this in .htaccess   
RewriteCond %{HTTP_HOST} !^siteB\.com$
RewriteRule ^/siteB  http://siteB.com/ [R=301]