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Networking concerns in virtual environments

Some months ago I bought a desktop system. I hadn’t had one for years, but a very strange and unexpected need came up; I wanted to play games with my son who lives in Greece, in an attempt to spend a bit more time with him, even virtually.
I bought and built a desktop system based on AMD’s excellent Ryzen line, but that’s for another time. On that computer, and as it would be used predominantly for games, I installed MS Windows. That is another thing that hadn’t happened in my household for decades!

Of course being who I am - and among others, not a big fan of gaming - it was not even a couple of weeks before several Linux virtual machines started popping up. Initially on Hyper-V as it was more than enough for the job, but when the need for the first VM with a graphical user interface - a Kali Linux box - came up, I switched to VirtualBox. The main (maybe the only?) reason was that Hyper-V has an annoying bug: it doesn’t support bidirectional clipboard with Linux guests.

VirtualBox has come a long way since I last used it. In the end of March, a message came up when I tried to update my Kali box:

Hash sum mismatch

A security person never dismisses such a message, although I understand how this can happen if I try to update at the same time the mirror syncs the packages. That should normally be resolved in ~5 minutes, but in my case, the problem persisted.

I switched Kali repository mirrors and manually selected one that had current updates. The problem didn’t go away. I started searching and trying to fix it following advice on the internet - the most common of which was to scrape the apt cache and lists. To no avail.

During this search, I found out that people behind network filters were among the ones affected. And then I remembered reading about a recent Microsoft update that was messing up with the network stack. My computer didn’t have network issues. It seems and still does seem to work flawlessly. But installation of a Windows patch to the host machine and a reboot, allowed my Kali virtual machine to retrieve updates without the dreadful Hash sum mismatch error message.

Coincidence? Maybe. But in any case, I now add to my troubleshooting playbook the probability that even when things seem (and should) be unaffected by the virtual network stack, I should also try to troubleshoot the host machine.

Tagged in : networking, security

2 comments

ithr0n
Sat, 27 Jun 2020 23:46

Hey, I experience the same issues with Kali and ParrotOS (probably every guest OS, because it looks like a host related problem as you said). I also use VirtualBox on Windows 10 host. Do you remember which Windows Update solved the problem? Was it really only the Update or did you change any other configuration on your host? Best Regards

Michalis
Mon, 29 Jun 2020 07:51

Hey ithr0n, I do not remember the specific patch, but it should be solved by now.

If it's not solved, you should look into Hypervisor settings on your computer. From "Turn Windows Features on or off" on your computer, try different settings for "Hyper-V", "Virtual Machine Platform" and "Hypervisor platform".

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