Using a VirtualBox VM to operate a network device for your Mac

VirtualBox running TinyCoreLinux, operating the RTL8187 wifi adapterI recently wrote about our long-range USB WiFi antenna over on Technomadics, which is the nifty little device that we use to connect to the Internet while we’re travelling. It’s great, but — and it’s a kinda large but — the OS X driver (it’s an RTL8187) is just mind-blowingly appalling. It crashes very frequently, I can’t sleep my Mac at night without unplugging the device, and when I plug the device back in in the morning, nine times out of ten I need to reboot. Plus, I have to run the whole system in 32-bit mode because the driver is ancient. Realtek refuse to assist, so that’s that.

Three thousand reboots later, I decided enough was enough, and set about seeing if I could run a virtual machine with a small Linux installation which operated the card on behalf of my Mac, and shared the resulting Internet connection. It was a long learning curve, but I managed to get it all working quite satisfactorily, along with an Internet Sharing setup on my mac to share the connection onwards to other machines on the local network.

What’s more, the drivers I’m using under Linux — actually, they’re Windows XP drivers, running under the fantastic ndiswrapper utility — are brilliant, and I get much better signal strength, stability and throughput, to my great surprise.

If you’re in a similar situation, and either have a crappy driver to contend with, or no driver at all, or even just want a more solid firewall between you and the dangerous open WiFi world, here’re some instructions on how to get it set up, along with a virtual appliance I put together to make it all happen.

A warning in advance: This is Linux, so it aint for the faint of heart. If you’re not familiar with Linux, by all means give it a go, but be forewarned that if everything doesn’t work for you out-of-the-box, it is a steep learning curve.

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Avoid the clobber: Nest your network activity indicator updates

On the iPhone, when you are doing anything that uses the network, you’re supposed to let the user know something’s going on, via -[UIApplication setNetworkActivityIndicatorVisible:]. This takes a boolean.

That’s all well and good, but if you have more than one object in your app that may do things with the network simultaneously, you’re going to clobber yourself.

A nice and easy solution: Maintain an activity counter and create a category on UIApplication to maintain it, and show or hide the indicator as appropriate. Then, whenever you start doing something with the network:

[[UIApplication sharedApplication] showNetworkActivityIndicator];

…And when you’re done:

[[UIApplication sharedApplication] hideNetworkActivityIndicator];

Here’s a category that’ll do it:

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The Making of Talkie: Multi-interface broadcasting and multicast

Part 2

TalkieTalkie is my newest product, a Walkie Talkie for iPhone and Mac.

In Part 1 of this series, I wrote about basic broadcasting. This works fine with one network device, but it’s worth discussing how to send through all devices, so you can communicate with others connected via, say, Ethernet and WiFi simultaneously.

So, in Part 2 I’ll write about the approach I took in Talkie for broadcasting from all network devices (a.k.a. network interfaces), so that one can communicate with others connected via WiFi, Ethernet (on a Mac), and any other network devices simultaneously.

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The Making of Talkie: Broadcasting

Part 1

TalkieTalkie is my newest product, the result of a collaboration with a good designer friend, Tim Churchward, who did the user interface.

Talkie is a little different from many of the other walkie talkie applications on the App Store (aside from the fact that much of it was written by me from our motorhome in Tunisia!), and I thought I’d write a little about some of the tech underpinning the app, and some of the choices we made. Along the way it may get a little tutorial-esque.

  • This first part will introduce our initial motivations, and will talk about basic broadcast communications — the broadcast communications part may be very familiar to some, in which case it may be worth skipping to the next instalment.
  • In the second part, I’ll continue the theme of networking, and will talk about what I ended up with for Talkie’s network code after addressing a couple of things, including switching to multicast.
  • Finally, I’ll talk audio, dual platform development, and anything else I think of along the way (Actually, I’m aching to talk about one particular upcoming feature that had me jumping up and down when I first thought of it, but for now, mum’s the word on that one.)
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Using custom DNS servers from the iPhone and over Internet Tethering

For those of us the roam around on network connections, OpenDNS and Google Public DNS provide public DNS servers which offer better security than using arbitrary DNS that’s assigned to us when we connect to a network. This means that rather than trusting the assigned DNS server — which could be a malicious third party that’s attempting a man-in-the-middle attack — we always use a trusted server.

In OS X, normally, one can specify custom DNS servers in Network Preferences, but when using Internet Tethering with the iPhone, no options are available.

It’s possible to set DNS configuration on the command line, though, as mentioned in this MacOSXHints article.

This technique can be used within a shell script to make things easier.

As it happens, if you have a jailbroken iPhone, the trick works there too — just ssh in as root, copy the script over, and run it from the iPhone.

The one caveat is that the DHCP client both on the iPhone and on Mac OS X will routinely reset the servers — I haven’t found a way to combat this yet, other than routinely re-running the script.

We have been using mobile broadband from my iPhone while we’ve been travelling; our current provider seems to go offline almost every evening — a quirk which I’ve just discovered is related to their faulty DNS server.

Using Google’s public DNS servers instead fixes this problem, so I was after a way to configure both the iPhone and OS X to use the servers.

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Links for February 10th through February 27th

Links for February 10th through February 27th:

  • TinEye Reverse Image Search TinEye is a reverse image search engine. You can submit an image to TinEye to find out where it came from, how it is being used, if modified versions of the image exist, or to find higher resolution versions.
  • Traffic Shaping in Mac OS X | Mac Geekery "…Create several pipes that have a set bandwidth and other properties for all packets that get filed into them; you then add queues to those pipes that determine what priority certain requests will get in that pipe; then you add actual firewall rules to identify packets and file them into queues."
  • Brandon Walkin » Introducing BWToolkit BWToolkit is a BSD licensed plugin for Interface Builder 3 that contains commonly used UI elements and other useful objects. Using these objects is as simple as dragging them from the library to your canvas or document window. In particular, "No Code" preferences window and tabbed sheets.
  • Aussie iPhone app developers and the IRS? Discussion about tax details for Australian iPhone developers. It appears the advice from Apple on the tax form is incorrect for sales on the App Store.
  • google-toolbox-for-mac – How to do iPhone unit testing This is a quick tutorial on doing iPhone unit testing using the facilities in the Google Toolbox For Mac
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