I've wanted to switch to nftables on some of my systems but found that some software or other depended on iptables (e.g. Docker Engine, Proxmox). Use nftables if you can get away with it but iptables-specific knowledge is still extremely relevant.
For the most part iptables is no more, iptables tools are now just wrappers to nftables. Technically you can still write iptables rules, and they will show up in nftables. Wouldnt recommend long term but its a good way to see the translation
> If someone doesn’t know iptables, they probably are not required to know it.
That makes no sense. Just because I do not know X, it does not necessarily follow that I am not required to know it, not at all. I might need it for my job, or my future job. I might need it for a Linux distribution I just installed, and so forth. Or perhaps I am already using iptables, but I do not know it.
Ahhhhhh at least an understanding that it exists and how it might interact with nft is probably beneficial unless they’re expecting to only ever work on greenfield equipment. If you were to walk into a job with existing IT infrastructure, there’s a solid chance that you’ll encounter iptables. If you’re looking to do a deep dive into something and learn it well, definitely nft is the way to go but being able to tweak iptables configs without needing to start over with a clean nft slate is valuable.
To your C++03 analogy, I wouldn’t recommend learning C++03, but I also wouldn’t recommend solely learning C++23 either. C++20 and 23 have some really cool stuff in them that can definitely make your code cleaner, but there’s a lot of codebases that are stuck on older versions (at $JOB one of our target platforms is stuck on C++17 and will never get an upgrade so we can’t move the codebase forward until we abandon that kit).
https://www.frozentux.net/iptables-tutorial/images/tables_tr...
I couldn’t find one that annotated where sysctl configurable were shown. But this is a useful annotation, even if it’s an exercise for the reader.