Biz & IT —

The power of two: use your iPad or iPhone as a mobile file server

Getting access to the filesystem on an iOS device is just an app download away.

Avatron's Air Sharing turns your iPhone or iPad into a mobile file server, overcoming one of the limitations inherent to the locked-down iOS filesystem.
Avatron's Air Sharing turns your iPhone or iPad into a mobile file server, overcoming one of the limitations inherent to the locked-down iOS filesystem.

For all the talk about a “post-PC” world, most people use smartphones or tablets as an addition to their existing technological arsenal, rather than a replacement for a standard laptop or desktop. In fact, there are a number of ways to combine the capabilities of your PC and mobile device that can make your tablet or smartphone an even more powerful tool. Last week, we took a look at an app that would let you use your iPad as a second monitor; this week, we'll talk about ways to use your iPad and iPhone as mobile file servers.

One of the useful features of the original iPod line was that the media players could also be used as external hard drives to transfer files between computers, a feature not to be discounted in those pre-Dropbox days. The iOS-equipped descendants of the iPod have shed those features, presumably to keep people from messing around with the devices' filesystems—iPhones, iPads, and iPod touches will be recognized as digital cameras by file explorers and most other programs, but you can't use them to move any old file around as you could with iPods of yore, at least not natively.

Luckily, apps exist to circumvent this limitation: there are a few, like Phone Disk, that will let you mount your iOS devices as external drives just as you could before, which is fine if you can install the client software on every computer you interact with, but what if you're trying to get your files on to a computer on which you don't have administrative access? In this case, turning your phone into a mobile file server makes it much easier to connect to from any computer.

Installing Air Sharing

One of the most versatile mobile file server apps is Avatron's Air Sharing, an app which essentially turns your iPhone or iPad into a mobile file server. At $6.99 for the iPhone version, $7.99 for the iPad version, or $9.99 for a universal app, it's a little pricey, though there's nothing to prevent you from running the iPhone version on your iPad to save a few bucks as far as I can tell. Once purchased and set up, the app will let you use your device to move basically any type of file between computers and other devices running Air Sharing, either by connecting to the phone from a computer using WebDAV or Bonjour, or by connecting from the phone to a computer capable of running both SSH and SFTP (available natively in OS X and via third parties in Windows). Support for cloud storage servers like Dropbox, Box, and Google Docs is also included—directions for connecting to these various service and operating systems is included in the app's extensive documentation.

Uploading a file from a computer using Air Sharing. You can also mount the phone as a WebDAV server on any operating system that supports the protocol.
Uploading a file from a computer using Air Sharing. You can also mount the phone as a WebDAV server on any operating system that supports the protocol.

Starting up Air Sharing for the first time will show you an impressive and thorough list of documentation that will walk you through connecting to computers with Air Sharing, and connecting to your phone from just about every desktop OS and Web browser under the sun. Press "Done" to show the phone's file structure and expose the app's controls.

You can view your device's Bonjour name and IP address at any time by tapping the wireless icon.
You can view your device's Bonjour name and IP address at any time by tapping the wireless icon.

The app is ready to use out of the box. Pressing the wireless icon at the bottom of the screen will show your phone's Bonjour name and IP address for your convenience. It doesn't require a password by default, so you'll probably want to go to Settings to change that before you start using it. Here, you can assign a username and password to be used when connecting to your "server," set a passcode to be entered when the app is launched (independent of the screen lock passcode), enable and disable access to the app's Public folder, and change the view settings for its file browser.

Mapping our Air Sharing "server" from Windows.
Mapping our Air Sharing "server" from Windows.

Once you've added a username and password, you can map the phone or tablet as you would any WebDAV server—the exact method varies from OS to OS, but the extremely thorough documentation lays it out in detail for you. Even more useful is Air Sharing's Web client, accessible by typing your device's IP address into any browser—you can easily download and upload files quickly and easily from any operating system.

Using Air Sharing's Web client is probably the easiest way to connect to your server from a computer you don't normally use, though it lacks the file explorer integration you get with WebDAV drive mapping.
Using Air Sharing's Web client is probably the easiest way to connect to your server from a computer you don't normally use, though it lacks the file explorer integration you get with WebDAV drive mapping.

When copying files, be aware of how much free space you've actually got on your phone or tablet—the software isn't particularly good at relaying your device's amount of free space to your desktop operating systems. Connected via WebDAV, OS X saw 22.52GB free and Windows saw 40GB free on a phone that actually had 20.2GB free.

Air Sharing's built-in file explorer can be used to create folders, import photos, and download webpages to your device.
Air Sharing's built-in file explorer can be used to create folders, import photos, and download webpages to your device.

The software has a few other caveats as well: for one, the app needs to be actively running on your phone or tablet for your computers to see it—if the phone goes to sleep or if you start using another app, Air Sharing will be suspended to save memory and your computers will lose their connection (in the app's settings, you can set it so that your device will never sleep while the app is running, though this is obviously done at the expense of battery life). Also, since the file transfers are happening over WiFi, your transfer speeds will typically be worse than they would be over USB.  If these minor annoyances don't discourage you, your iPhone or iPad can make for a decent external drive in a pinch.

Channel Ars Technica