Ossec can't block brute force attack

[apsalsaa]

Hello, i have problem with blocking attack, please check this condition and help me, thanks in advance
I've installed ossec 3.7.0 version on my server and attacking the server with hydra brute force, slowloris, and arp sniffing, i did not change anything after installing ossec so the ossec.conf and the rules still by default, but my server cannot block the brute force attack and arp sniffing, there is no alert response and nothing can be seen on active-responses.log. Any solution for this problem?