If your database stores user-generated content along with client IPs, you may need a way to detect and block abusive users. A common approach is to analyze database records to identify IPs with excessive activity, group them by subnet, and apply firewall rules to mitigate potential abuse. First, we retrieve a list of IPs with multiple records over the past 21 days that exhibit patterns of potential abuse—such as frequent spam submissions, excessive requests, or other suspicious activity.

In case you need to quickly ban a list of IP addresses from connecting to your server, iptables is perfect for the job. iptables is a user-space firewall that can control incoming and outgoing connections with policies and filter rules. Blocking ingress from a single IP is easily done with a single iptables rule. We can use this same command to automate the creation of many rules with a bash script that will read our list of IP addresses from a file.