Online Only Dropbox

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  1. Dropbox Online Only Option
  2. Making Dropbox Online Only
  3. Dropbox Sync Windows
  4. Dropbox Keep Files Online Only
  5. Turn Off Online Only Dropbox
  6. Dropbox Online Only Doesn't Work

Move stale files and folders to online-only. They’ll still be visible and accessible from your desktop, even though they’re off your hard drive. Works on multiple platforms Smart Sync works seamlessly on Windows and Mac, even if you’re not on the latest version. We are excited to use Smart Sync by having all our client folders shared to all of our team as 'Online Only' as default so we can use Dropbox in the same way we used our traditional physical file server. Ie all client folders browsable by all team members and Smart Syncing files where needed without the need to manually share project folders each time. Dropbox Uploader is a BASH script which can be used to upload, download, delete, list files (and more!) from Dropbox, an online file sharing, synchronization and backup service. It's written in BASH scripting language and only needs cURL.

  1. Doesn't Dropbox stop you from doing this? If it still does, you have to use MKLINK /J%Cfolder%%external% Where%cfolder% = something like c: external. And%external% is the location of your hard drive. After you do this, then tell Dropbox that this is the location of your Dropbox and link your account.
  2. Login to Dropbox. Bring your photos, docs, and videos anywhere and keep your files safe.

How safe is your data when you plunk it down into Dropbox? Where does it go? Who can see it? There have been concerns raised about Dropbox’s security in the past, so we’re going to take a look and see if they’re concerns worth having.

Expand Table of Contents

What is Dropbox For?

Dropbox synchronizes your files across multiple devices. Just put a file in the Dropbox folder and voila! It puts a copy on all your computers. And when you make changes to a file, it makes the same changes on all the others.

There are many services that offer this functionality (Cubby, SpiderOak, Google Drive, Microsoft SkyDrive, etc), but Dropbox was the first to make it big.

How Does Dropbox Work?

Is it magic? No, silly. Dropbox, like its competitors, uses the internet to keep your files synchronized. It doesn’t matter where they are. You could have computers on opposite sides of the world and it would still work, as long as they both have Dropbox installed and an active internet connection.

It’s all managed by an unseen server that sits in the middle of everything. When you put a file in Dropbox, it’s first uploaded to their server and stored there. Then, it pushes the file out to all your other devices. It always sends the files to their servers first, even if both computers are in the same room.

How Dropbox Does Security

You can probably spot the weaknesses in the process. Any time you send your data anywhere on the internet, you’re assuming risk. What’s more, it’s stored on a central computer that you have no control over. This requires that you trust in the company to treat your data properly.

So is Dropbox doing everything the right way? Let’s take a look at their security process.

  1. The Dropbox client (program) is installed on your computer. This program is what creates a secure connection between your computer and their servers.
  2. Dropbox encrypts the data on your computer in preparation to send it over the internet using the industry standard SSL/TLS with AES 128-bit encryption.
  3. Your data is copied to the Dropbox servers and decrypted once it reaches its destination. Thanks to the encryption performed in the previous step, no eavesdroppers will be able to read your data as it zooms over the internet.
  4. Your data is then encrypted again for storage with AES 256-bit. This is to prevent hackers from seeing your data if it’s stolen from their servers.
  5. The data is then copied from the servers to your other devices over the internet. Again, using SSL/TLS encryption.
  6. Once on your computer, your data is then decrypted and stored on your hard drive.

What’s the Problem With Dropbox’s Security?

All that encryption sounds pretty safe. So what’s the problem?

The biggest issue raised with most services like Dropbox is that you’re not the only one with access to your data, despite all the fancy encryption maneuvers. It’s actually possible for Dropbox to manually decrypt and look at your data while it’s on their servers. This can lead to several issues:

Dropbox Online Only Option

  1. A rogue Dropbox employee who decides he wants your data
  2. Of minimal concern since very few employees typically have the access rights. But still, you should be aware that it’s possible for others to see your data.

  3. Hackers getting their hands on your encryption key
  4. Since Dropbox stores the keys for all its users, it’s possible that a database breech could result in everyone’s encryption keys being stolen. Not likely since they’re probably stored far away from your actual data. But worth the mention nonetheless.

  5. Dropbox voluntarily disclosing your information to a third party
  6. This is the real concern. The question is whether companies like Dropbox should have the right to give away your data.

Making Dropbox Online Only

For instance, Dropbox has already specified that were they to receive a subpoena by law enforcement, they would willingly decrypt your data and hand it over. And what would you be able to do about it? Probably nothing, even though Dropbox’s own Terms of Service specify that you maintain full ownership of your data while it’s stored on their servers.

This may not rile you too much since you probably have nothing to hide from the cops. But it’s worth noting that nothing you put in Dropbox is private. Other eyes may someday see what you put in there.

If you are interested in higher security for your files, you can always encrypt your data using another program like AxCrypt or TrueCrypt before putting it into Dropbox. For step by step instructions see my AxCrypt tutorial. Alternatively, you can use a competing service like SpiderOak which does not have the capability to see your data as long as you’re using their client you installed on your computer (if you log in to their webpage to access your data then their servers do get your encryption key).

Dropbox Privacy Policy Highlights

Here are some of the main points of the Dropbox Privacy Policy in case you’re interested in more of the details.

  • Any personal information you give Dropbox is kept and stored
  • This is common practice for most online businesses. It includes anything personal you give them like names, phones, emails, credit cards, postal addresses, social networking info, etc.

  • Even if you delete your account, Dropbox reserves the right to retain your data
  • There are several reasons for this, such as if your data is tied up in legal obligations or disputes, but also if it’s needed to “enforce our agreements”, whatever that means. Also of concern: the backups of your data that Dropbox creates may not be deleted at all.

  • Your personal information is never sold to third parties
  • This does not mean it’s never shared freely (see next bullet).

  • Dropbox reserves the right to share your information in these circumstances:
    1. If you use another application to sign into your Dropbox account
    2. For instance, if you use Facebook to sign into your Dropbox account, Facebook gets your personal information from Dropbox. Dropbox does not take responsibility for what the other party does with it.

    3. If it’s required to provide you Dropbox’s services
    4. For instance, Dropbox uses Amazon’s S3 service for storage of your data, so Amazon gets your info, too.

    5. If law enforcement requires it
    6. If Johnny Law ever subpoenas Dropbox for your information, Dropbox will comply. What’s more, they’ll even completely decrypt your files for them before handing it over.

    7. Any situation that Dropbox decides is threatening to itself or its users
    8. This includes alleged fraud, property rights infringement, and even the threat of bodily harm to someone. This is a broad scope and allows them a lot of flexibility.

    9. If Dropbox is bought or merged
    10. Of course, if Dropbox is bought out, the acquiring company will get your info.

  • Dropbox does not use your location information (like GPS), but what it will do:
    1. Use the location information embedded in photos and videos you upload
    2. This shows you that Dropbox has the ability to look at the files you upload. You’ll just have to assume that they see it all.

    3. Approximate your location based on information like your IP address
    4. They’re still trying to locate you, even if it’s not as precise as GPS.

Is Dropbox Safe To Use?

The bottom line is that Dropbox has its uses, but in my opinion should not be used for everything. You have little to worry about unless you’re using it to store sensitive data. I suggest that you don’t use it for your passwords, credit cards, medical or tax records, embarrassing pictures, your next unpublished bestseller, or anything else that you wouldn’t want someone else to see.

It does provide good security against hackers and ne’er-do-wells. But the fact that they have the power to decrypt and see your data is significant. It means that anything you do with their service cannot be considered private. As long as you understand what it should and shouldn’t be used for, then it’s a service you’ll probably be happy with.

Related Articles

In this article…

  • How Smart Sync works: Supporting technologies
  • How to Disable Smart Sync

What is Dropbox Smart Sync?

The team at Dropbox says it best:

Smart Sync is a Dropbox feature that helps you save space on your hard drive. Access every file and folder in your Dropbox account from your computer, using virtually no hard drive space. Smart Sync is available for Dropbox Plus and Professional customers, and members of Dropbox Business teams.
Online only dropbox

And this short video discusses the considerable benefits of Smart Sync:

Indeed, Smart Sync has been a very popular feature since its debut in 2017.

How Smart Sync works: Supporting technologies

Smart Sync leverages a trio of Windows capabilities:

1. NTFS Sparse Files technology

NTFS Sparse File functionality allows Dropbox to create an “empty shell” for any file — with all the usual information (name, size, etc.) but with none of the actual content.

So when you create a file on, the file’s information (its “metadata”) is immediately downloaded to your computer but none of the file’s contents are transferred in that operation. As a result, you can see the file on your system but it consumes almost no space on your hard drive. Very efficient!

But what happens when you try to access the zero-content file? That’s where the next technology comes in…


2. Windows file system Minifilter driver technology

When you access a file in your Dropbox folder, demanding to see its content, a Windows Minifilter driver ensures that the file’s contents are quickly fetched from The arrangement is fairly technical, but the following example illustrates the basic concept.

Suppose you have an online-only file called “notes.txt” in your Dropbox folder. Its contents have not yet been downloaded to your computer. When you double-click on the file:

  1. Windows starts Notepad (the program associated with .TXT files), passing it the full path to notes.txt.
  2. Notepad calls the Windows API ReadFile function to grab the contents of notes.txt
  3. But before invoking ReadFile, Windows intercepts the operation and notifies the Dropbox Minifilter that a program would like to read the contents of notes.txt.
  4. The Minifilter, seeing that the file’s contents have not yet been downloaded, arranges for the file’s contents to be retrieved from and saved on the local PC.
  5. Windows next calls ReadFile, which returns the contents of the file.
  6. Notepad displays the contents of the file.

Most of the magic happens in step 4. The next section examines how that works.

3. Windows Interprocess Communication (IPC)

At first, we thought that the Minifilter component did all the heavy lifting, downloading content as necessary. However Dropbox says otherwise (the Minifilter is a “system extension”):

We don’t use system extensions to make network requests
We don’t use system extensions to parse any data in the filesystem
We don’t use system extensions to read or write files
Online Only Dropbox

Clearly the Minifilter isn’t downloading the files from So what’s doing it?

The answer: Dropbox.exe — the process run when you launch Dropbox on your desktop.

So when you request an “online-only” file not yet on your hard drive:

  1. The Minifilter receives the request.
  2. The Minifilter contacts the Dropbox.exe process and asks it to get the file.
  3. Dropbox.exe goes out to the Internet and downloads the file from
  4. Windows makes the file available to the user.

The Minifilter and Dropbox.exe interact using Windows Interprocess Communication — a collection of technologies supporting communication between different programs.

Now that we understand how Smart Sync works, let’s highlight three implications of the technical architecture.

Implication #1: Files cannot be downloaded without an Internet connection

This shouldn’t be a surprise.

Since files are fetched from the cloud as needed, you must be connected to the Internet to download files from

Dropbox confirms this limitation in their FAQ as well:

Can I access online-only content when I’m not connected to the internet?
No, online-only content isn’t stored locally on your computer. Connect to the internet to access online-only content.

Implication #2: Files cannot be downloaded if Dropbox isn’t running

As mentioned before, the Dropbox process (Dropbox.exe) plays a key role in downloading “incomplete” Smart Sync files. No file can be downloaded if Dropbox is not running.

To be clear, the Minifilter is always notified when you try to access an “online-only” file in the Dropbox folder. But if Dropbox isn’t running, there is no way for the Minifilter to download the file. The operation fails and you get a wonderful “Unspecified error” message (pictured here from the Dropbox forums):

Note that this behavior only occurs when Smart Sync is on. Without Smart Sync — where Dropbox synchronizes all files to your hard drive — each document you see on your computer is readily available whether Dropbox is running or not.

Implication #3: Files cannot be downloaded if Dropbox is running as a Windows Service

Perhaps the most subtle consequence of the Smart Sync architecture has to do with background operation. Specifically, the Minifilter and Dropbox must operate in the same Windows Session for the two to communicate.

Dropbox Sync Windows

This is not a problem when you use Dropbox interactively on the desktop. All components run in the single logon session and Dropbox downloads files on demand, as expected.

However, customers running Dropbox as a background Windows Service face a problem. Dropbox will be running in Session 0 (the home for all Windows Services), while the Minifilter will be operating in the user’s interactive session (for example Session 1). The components will not be able to communicate and the files cannot be downloaded or opened. The “Unspecified Error” will abound.

So if you’re running Dropbox as a Windows Service (perhaps with our AlwaysUp utility), you should definitely turn Smart Sync off. Read on to find out how to do that.

How to Disable Smart Sync

You have a couple of options. You can either disable Smart Sync for specific folders, or turn off the feature entirely.

Disable Smart Sync for a single folder

This video illustrates how to adjust your Smart Sync folder settings:

And here are the step-by-step instructions to disable Smart Sync for a specific folder only:

  1. Click the Dropbox tray icon () to open the Dropbox menu
  2. Click the folder icon in the upper right:
  3. Find the folder that you would like to change. Right-click that folder and select Smart Sync > Local from the menu:

That’s it. In a minute or two, the Dropbox process will notice the change and will download the entire folder to your hard drive.

Dropbox Keep Files Online Only

Turn off Smart Sync for your Dropbox Plus, Professional, or Business account

To turn off the Smart Sync feature entirely, please follow these instructions to opt out of the system extension on

Dropbox Business team administrators can deactivate Smart Sync by opting out here (sign in required).

Questions about Smart Sync? Need Help?

Turn Off Online Only Dropbox

Please get in touch and we’ll be happy to help — with this or any Dropbox feature.

Dropbox Online Only Doesn't Work

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