You may need to install the epel-release package first. Most Linux systems do not have the ipset utility installed by default. This way we can add multiple systems we no longer want to connect to our systems.

Using blacklists with iptables and ipsetĪnother option is creating a blacklist. You might even get a very long list of IP addresses to block after a while. Iptables -I INPUT -s 192.168.1.100 -j DROPĪlthough this option works great, it might not scale very well. This way traffic is no longer allowed from that particular IP address. The first option to permanently block an IP address is by creating a rule in the INPUT chain. We will use an empty ruleset for test purposes. The first step is to validate existing iptables rules. Time to get started and block some IP addresses! Check existing iptables configuration

This may come in handy when you get repeating port scans or see failed login attempts in your log files. We can use iptables to block one, multiple IP addresses, or even full networks. It is around for quite a while and is enabled by default within the Linux kernel.

Most system administrators will already be familiar with iptables. Blocking IP addresses and subnets with ipset

Ipset linux