Re: Clients cannot access the Internet after an OS upgrade.

[Narcis Garcia]

It's important you provide command line of your Qemu calls.


Narcis Garcia
El 7/11/20 a les 5:38, Cliff Pratt ha escrit:
> I'm posting this because it may help someone who ends up in the same
> situation as I did.
> 
> I run Ubuntu and before a recent upgrade, I was running 20.04. I had
> already installed Qemu and created a number of guests. I also had docker
> installed as a snap.
> 
> I upgraded Ubuntu from 20.04 to 20.10 and my guests stopped working!
> 
> After a LOT of digging around, I discovered that Ubuntu has switched to
> nftables from the legacy iptables portions of Netfilter. There are now
> two iptables versions - iptables-nft (which is aliased to iptables) and
> iptables-legacy.
> 
> For reasons which I do not understand, the snap docker version uses (or
> seems to use) the legacy version. It sets the policy of the FORWARD
> chain to DROP, and this causes the Qemu packets to be dropped.
> 
> The solution, for me, was to disable the docker snap for now.
> 
> There are obvious holes in the explanation above. Maybe someone with
> more knowledge of how these things interact with one another could fill
> in the holes, but the above may help someone.   
> 
> -- 
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