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I'm looking into setting up a mail server (running Ubuntu, ofcourse), but I need it to run reliably (in case it's good enough to start using it instead of only Gmail) so I found a VPS provider that seems trustworthy and that uses KVM, instead of my Ubuntu server at home. I want my mails to be stored safely and encrypted, as a precaution (though I know it won't protect against some hacker accessing it while it's still running). This is easily done by using Encfs (provided I log in and decrypt it after boot).

While doing research on running a mail server in a VPS, I learned that the provider (or a hacker) is always able to read what my VPS is doing. It was claimed (second paragraph) this is very easy to do if you're using OpenVZ, but if my provider (or more likely, if at all, a hacker) wanted to do the same with a KVM or Xen VM (s)he needs to reboot my VM. However, I couldn't find more information about this.

My question: If someone has access to my KVM VM and wanted to go through the data on my VM, what could that person read? For example, would that person just get a copy of my VM in an unbooted state, so therefore with the encrypted Encfs folder still locked when booted if they don't know my encryption password? Or could they access a running VM with the Encfs folder that I decrypted? (I hope my question makes sense.)

I know my provider or a hacker wouldn't be very interested in reading my e-mail, but better safe than sorry. GPG isn't that widely used yet.

Justgivemeaname
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Physical access is root access, so if someone has physical access to the server, regardless on if it is on a VM or bare metal, they have root access. In the case of KVM the owner of the bare metal host can access the guest. You can always encrypt the data, but, that may be of limited benefit as the data will be decrypted when you access it.

Same with the network. The owner of the VM can see your network traffic. Again you can encrypt some of the traffic (https, ssh, etc).

Panther
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  • Normally, the way I've planned it now, I will boot the VM, access the server by SSH and mount/decrypt my encrypted file. Once it has been decrypted, anyone with root access to the physical server also has access to my data on that file right away? – Justgivemeaname Mar 13 '15 at 09:56
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    That is correct. Depends on how the guest is set up, here are two examples - http://www.linux-kvm.org/page/9p_virtio and http://libguestfs.org/ – Panther Mar 13 '15 at 11:52