Problem with iptables on buster - neither legacy or nft work

Question

I recently installed buster on a Pi 3 Model B. Trying to setup a von (using pivpn) I realised that iptables is not working.

I've learned that there's legacy mode and nft. Here's part of the output from hostctl and what I get when I run either version. I've tried updating and upgrading with apt.

  Operating System: Raspbian GNU/Linux 10 (buster)
            Kernel: Linux 4.19.93-v7+
# iptables-nft
iptables/1.8.2 Failed to initialize nft: Protocol not supported
# iptables-legacy -L
iptables v1.8.2 (legacy): can't initialize iptables table `filter': Table does not exist (do you need to insmod?)
# iptables-legacy -m comment
iptables v1.8.2 (legacy): Couldn't load match `comment':No such file or directory

I find it hard to believe that I am the only one experiencing this, but I really don't see anything helpful on the web (there are a couple of posts but no solutions). I was going to try to downgrade iptables, but from what I see there isn't an older version packaged for buster to do that.

Answer 1

One of those days ... although the pi was recently booted, it seems that it needed a reboot - probably after some update?

When I was troubleshooting, I had

ls /lib/modules/$(uname -r)
ls: cannot access '/lib/modules/4.19.93-v7+': No such file or directory

After more research, I figured maybe a reboot was required, after that I had

# uname -r
4.19.97-v7+
# iptables -L
Chain INPUT (policy ACCEPT)
target     prot opt source               destination

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination