KnowCardLinux · Firewalls (nftables & firewalld)
What are the three ways to feed rules to nft, and what makes a rule file self-executing?
Answer locked. Get the free KnowCard app to reveal it — plus spaced-repetition review so it actually sticks.
More in Firewalls (nftables & firewalld)
On a fresh openSUSE install the firewall is already blocking almost all outgoing traffic, and the built-in YaST firewall module is missing your Ethernet interface. What is the recommended way to fix rules?
You want to run a custom service on port 900 versus port 2000. Why does one of those choices require root and the other does not?
Where does a Linux system map friendly names like ssh, http, and https to their numeric IP port numbers?
A colleague says every IP service confirms receipt of packets. Which common protocols contradict that, and why does it matter for firewall rules?
You want a quick list of which ports your local machine is actually listening on, including the owning process. Which netstat invocation gives that?
You need to find which process is holding a specific network port, say port 22. Which command targets that directly?
Start learning today
Free to start — download the app or use it in your browser.