This little shell script will filter out spammy IPs that are used to send spamm serach requests to your Magento store. You can read more here https://upment.com/magento/how-to-block-spammy-search-query-requests-that-land-on-magento-1-9-x/
- Haproxy - load balancer
- APF - APF (Advanced Policy Firewall) available at https://www.rfxn.com/