Was looking for some quick examples to block access to URL’s based on a rewrite rule and found this blog post: http://www.netshinesoftware.com/blog/restricting-access-to-a-url-by-ip-address-using-mod-rewrite/ I’m copying the best bits here for easy reference.
Redirect traffic from specific hosts with specific query string
RewriteEngine On
RewriteCond %{REMOTE_ADDR} ^123\.255\.123\.255 [OR]
RewriteCond %{REMOTE_ADDR} ^124\.255\.124\.255 [OR]
RewriteCond %{REMOTE_ADDR} ^125\.255\.125\.255
RewriteCond %{QUERY_STRING} option=com_my_special_component [NC]
RewriteRule ^(.*)$ index.php [F,L]
Don’t redirect traffic from these hosts with specific query string
RewriteEngine On
RewriteCond %{REMOTE_ADDR} !^123\.255\.123\.255
RewriteCond %{REMOTE_ADDR} !^124\.255\.124\.255
RewriteCond %{REMOTE_ADDR} !^125\.255\.125\.255
RewriteCond %{QUERY_STRING} option=com_my_special_component [NC]
RewriteRule ^(.*)$ index.php [F,L]