docs: Fix command for overwriting iptables on kube-proxy replacement install

[Stijn98s]

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Updated the restore iptables command because this command wasn't working on Ubuntu 20.10 arm64.

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[qmonnet]

Thanks! The change looks good, but I would be curious to understand why the previous command wouldn't work. What error did you get?

[Stijn98s]

Didn't get a clear error. The changes didn't got applied. These errors occured.

Can't open /dev/fd/63: No such file or directory
and
Warning: iptables-legacy tables present, use iptables-legacy-save to see them

But with this command the changes got applied.

[qmonnet]

Ah, did you run the command with sudo? Process substitution might be at play here.

If so, let's update the command indeed to avoid other people to hit the same issue.

[Stijn98s]

Yea, added sudo to both commands. Still didn't work

[qmonnet]

Yes, I suppose this is because of the sudo that the <(...) syntax didn't work. See the answers I linked if you want the details. All good for me!

[aanm]

@qmonnet but wouldn't we need something like sudo iptables-save | grep -v KUBE | sudo iptables-restore? at the very least: sudo su -c "iptables-save | grep -v KUBE | iptables-restore"?