Blocking access to admin CI panel via .htaccess

[eluser]dimaomni[/eluser]
Hi,

How to block access to http://domain.com/admin/main/ admin panel via htaccess ?

I tried like below, but it is not working.

RewriteEngine on

RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule .* index.php?/$0 [PT,L]

RewriteCond %{REMOTE_ADDR} ^1\.1\.1\.1$
RewriteRule /admin/main [F,L]