<VirtualHost IP:81 >
ServerName site.ru
...
<Files "admin.php">
Order deny,allow
Deny from all
Allow from 127.0.0.1
Allow from МОЙ_IP
</Files>
</VirtualHost>
[Wed Aug 30 21:15:35 2017] [error] [client МОЙ_IP] client denied by server configuration: /.../admin.php