On amazon.com I found some personal cloud NAS products and was wondering how some of them work. In this article the author discusses the My Cloud app and how it can be used from any internet connection to download the data save on the the personal cloud. Doesn't that make it not personal anymore, because doesn't the data have to go through WD's big server? Otherwise how can a simple NAS act as a server without having a static ip (etc.) configured?

Basically I'm asking, how can these devices be accessed from anywhere and still be secure and private? To quote one review

Once I downloaded the WD MyCloud app to my iPhone, it was game on...The first time I clicked on the share that my music was stored on while I was driving in the car

how does this work?

2 Answers 2


The data is stored locally on your drive and not transferred to them.

I believe they use OpenVPN in some way (that is transparent to the user), so that when you link it to their online service, it connects back to your local drive.

So they do not store your data, but they do hold the keys to your drive. If you were concerned about this, you could disconnect the NAS drive from their online service, and use your own VPN if you need to access the data remotely.

  • Yea I guess that makes sense, if you can disconnect from their online service.
    – Celeritas
    Nov 20, 2015 at 1:33

There are a few different ways this could work:

  1. They copy everything from your drive to a big server that they control. This seems unlikely - it would involve them having to run a lot of secure storage areas, to use up lots of bandwidth syncing data, and probably fall foul of some data protection laws, even if it was encrypted.
  2. They run a service like DynDNS, where the drive connects to a server they control and effectively says "I'm at this IP address now", and when you connect from another device, the server says "you need to talk to that IP now". This avoids the need to copy data, and, depending on the setup, could easily involve encrypted connections from the accessing device to the drive. This still involves a server, but only for lookup. I suspect this is the used method.
  3. The small print on the box specifies "Data only available when drive connected to to static IP address". This would avoid the need for a server, but would probably upset a lot of people who brought them!
  • In scenario #2 would this somehow make your home network a target by exposing it to the internet? Or would their server only hand over the IP address after some sort of challenge response (ie username/password) is entered?
    – Celeritas
    Nov 20, 2015 at 1:35
  • Your IP address should be considered open information anyway - it's trivial to scan the whole IPv4 range. If the device is responding to requests, your home router must be forwarding ports to it in some way, so there is always potential for something to go wrong. The only way to avoid that would be for the device to regularly ping a server to see if there have been requests for data.
    – Matthew
    Nov 20, 2015 at 6:47
  • Right so wouldn't a phone connecting remotely to the NAS required forwarded ports on the router? Or would this be the regularly pinging approach?
    – Celeritas
    Nov 20, 2015 at 6:58
  • There is a standard protocol for allowing devices to have ports forwarded to them - upnp - so an end user wouldn't need to manually set up a port forward. The router would automatically do it, which can be a bit of a risk if any untrusted devices are connected to the local network.
    – Matthew
    Nov 20, 2015 at 7:01

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