I am not sure at all what your log looks like -- the link you sent requires login -- but I suspec the 'identified by bot*' bit refers to the user agent of the remote system accessing yours.
In PHP, you can check the user agent of a remote user and just [man]die[/man] based on what you find there. This is not especially powerful because the remote user can report whatever they want in this value because it is (optionally) supplied with each page request.
$user_agent = isset($_SERVER['HTTP_USER_AGENT']) : $_SERVER['HTTP_USER_AGENT'] ? "";
if (strpos($user_agent, 'bot*')) {
die("Sorry, access is not permitted");
}
The remote address can also be used to filter your remote users. phpBB and other open source projects usually let you maintain a ban list of ip addresses (or ip ranges) that let you deny access to all kinds of remote users. How you implement it is up to you:
$remote_address = isset($_SERVER['REMOTE_ADDR']) : $_SERVER['REMOTE_ADDR'] : "";
if ($remote_address == '11.22.33.44') {
// note that banning a single ip address this way is not very powerful.
die("Sorry, access not permitted");
}