You just provisioned a fresh Linux server. Within minutes, the SSH brute-force bots will arrive.

There are too many ways to build a firewall in Linux. I wrote a practical guide to the four major tools: iptables, nftables, firewalld, and ufw, including their mental models and deployable configs.

Also includes a deep dive into the "Docker Trap" (why Docker silently bypasses your default-deny rules) and how to fix it.

(And yes, I still spend the intro and conclusion reminding everyone that FreeBSD's PF is the undisputed king of packet filtering. Let's argue in the replies.)

Read it here: https://blog.hofstede.it/linux-firewalls-how-to-actually-secure-a-cloud-server-iptables-nftables-firewalld-ufw/

#Linux #Sysadmin #DevOps #Security #Netfilter #Docker #Networking