Iptables is the name of the firewall built into the Linux kernel. It is also the tool used for firewall configuration. This post explains how to use iptables with a range of IP addresses and/or ports. It could be used, for example, to allow SSH traffic from a number of systems. Or to open up a range of ports with a single firewall rule.
The Linux firewall (part of the Netfilter project) is important on Internet facing systems, “edge” servers and “jump” boxes. Particularly when they do not sit behind another protective network element such as a load balancer or discrete firewall. For example, standaline cloud instances that are not part of a protected VPC infrastructure. Continue reading