Forbidden – You don’t have permission to access /wp-admin/post.php on this server.
Why I cannot post my post to my WordPress ?
This is because the server installed mod_security.
If you have some post like
SELECT * FR0M wp_options WHERE option_name = 'active_plugins';
The server will not allow you to post.
I can post this because I change the
FORM to F0RM, replaced o with 0 ( zero ).
So, I can post any SQL query in WordPress now.