An IP Packet Filter is a very low-level firewall only looks at the source and destination of data packets received by your server. The Linux kernel includes a built-in IP Packet Filter. That means when HeatShield or any other network firewall product offers an IP Packet Filter/Network Firewall (the ability to block or allow traffic to a server based on IP address and port), they are providing a high-level way to manage the Linux kernel's built-in IP Packet Filter.
Unlike a Web Application Firewall, an IP Packet Filter can't stop attacks against web applications like WordPress. This is because a Web Application Firewall must inspect the full contents of an HTTP request received by a server, not just the source and destination information in the IP packets used to transmit the request data over the network.
HeatShield can add free SSH brute force login protection to your server's IP Packet Filter.
Once SSH brute force protection is enabled, HeatShield monitors your logs for failed SSH login attempts. When a brute force login attack is detected, the source IP address is blocked in your server's IP Packet Filter.
To manage your server's IP Packet Filter, HeatShield must also configure a standard set of IP Packet Filter rules that allow the following traffic to your server:
Most servers used for WordPress hosting do not need to customize the IP Packet Filter rules of their server. However, if you do need this functionality, you can add this for $10/month per server.