>  Read raddb/policy.conf.  Look for "do_not_respond"
Hello Alan,
Thank you, it solved the issue. I'm just not sure if I've implemented
it in right way:
authorize {
        ....
        ldap {
# I don't understand next line:
                fail = 1
        }
        if (fail) {
                do_not_respond
        }
        .....
}