Category Archives: Uncategorized

Arduino, Chromebook, Linux, Uncategorized

Howto: Setup Arduino on Chromebook

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Background

Arduino is an interesting microcontroller platform / board that arguably launched the era of low cost, standalone microcontroller systems. At this time, there are a multitude of these devices in the $50 less price range – but the Arduino was one of the first.

ArduinoUno_R3_Front_450px

The Arduino is an 8 bit microcontroller with a USB interface, a GPIO interface, A/D and D/A converters, I2C interfaces, and UART(s). More importantly, it has a free and easy to use IDE that supports C coding for the device. The Arduino Uno runs about $25 (at this time) from a number of sources – AdaFruit or Sparkfun (for example).

In any case, this post will (hopefully) be relatively short and provide a proof of concept that the Arduino system can be installed and function on the Chromebook 14.

Dependencies / Assumptions / Caveats

This install requires that:

  1. The target Chromebook 14 is in developer mode.
  2. It has an SD card of at least 8GB to support the installation of a crouton chroot Ubuntu install.
  3. A fairly recent version of Ubuntu installed to a crouton chroot jail – for details refer to my post on installing an Android Development Environment.
  4. Java JDK installed and functioning. Once again – refer back to the Android Development Environment post.
  5. An Arduino device to test with.

Note: All of the instructions below are based on name of my user (joeuser), the name of my SD-Card (chrome-32), and particular versions of the install packages. You will need to modify for your respective names / versions.

Hardware – Arduino / USB Interface

My biggest concern with Arduino on the Chromebook is whether the Arduino Uno (my test board) will be recognized / configured correctly by ChromeOS – since there is a real risk that the appropriate kernel drivers may not be included on ChromeOS. Our chroot Ubuntu jail still uses / depends completely on ChromeOS for the kernel, kernel drivers and /dev.

So the first thing we are going to do is see what the ChromeOS kernel messages are when we hotplug the Arduino Uno into the Chromebook. Taking a look at the before by opening a crosh window <ctrl-alt-t>, followed by:

chrosh>shell
dmesg

Produces a screen full of device messages. Interestingly the last message indicates that  a GSM modem is mapped to ttyUSB0 – information that may be useful in the future. In any case, if we plug in the Arduino Uno to a USB interface on the Chromebook and run ‘dmesg’ again (looking specifically for new messages), we get the following information.

[12028.022309] usb 1-1: new full-speed USB device number 39 using xhci_hcd
[12028.035738] usb 1-1: New USB device found, idVendor=2341, idProduct=0001
[12028.035752] usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=220
[12028.035763] usb 1-1: Product: Arduino Uno
[12028.035771] usb 1-1: Manufacturer: Arduino (www.arduino.cc)
[12028.035779] usb 1-1: SerialNumber: 649323436383514051E1
[12028.035970] usb 1-1: ep 0x82 - rounding interval to 1024 microframes, ep desc says 2040 microframes
[12028.036424] cdc_acm 1-1:1.0: ttyACM0: USB ACM device

Which provides us with a couple of useful datapoints. Specifically, that the device is recognized as an Arduino Uno, and that it is mapped to ‘ttyACM0’ – implying that it is recognized and likely supported by kernel driver.

The next thing we want to look at is is what it looks like in /dev – which is where the tty devices are mapped. In order for this interface to function correctly, the devices needs to readable / writeable from the Arduino IDE, and that will be installed on an crouton chroot Ubuntu install. So – to be more specific, we need to see what the ‘/dev/ttyACM0’ device looks like from inside of Ubuntu on the Chromebook – ownership and permissions. Start the Ubuntu install, switch to that interface (VT3) and open a terminal window. Inside that window, enter:

cd /dev
ls -al tty*

And this produces a listing in which the line of interest looks something like:

crw-rw---- 1 root serial 166,  0 Nov 26 05:37 ttyACM0

Note that the line containing ttyACM0 has permissions set to 660 and is owned by group ‘serial’. Most significantly, it is not world readable/writable. This will matter later when we need to access it from the Arduino IDE (Interactive Development Environment).

Software – Installing the Arduino IDE

There are multiple options for installing the Arduino IDE on Ubuntu. The easiest is launch the Ubuntu Software Center (or Synaptic)  from inside the Ubuntu system, search for Arduino and install. The only real issue with this is that the version in the Ubuntu respository is usually a few versions behind the most current version at the Arduino homepage. My suggestion is to try the version in the Ubuntu repository, see if it works (or doesn’t), and then evaluate the differences between the installed version and the most current version. If the updated features are critical to your needs, download and install the current version from the Arduino homepage – and follow the instructions for Ubuntu install.

After the install has completed, start start the Arduino IDE. I dialog box will popup indicating that the current user is not part of the ‘dialout’ group.   This can be remedied by closing the Arduino IDE, opening a terminal window and entering:

sudo usermod -a -G dialout joeuser 
sudo usermod -a -G serial joeuser

Which of course is based on my default username ‘joeuser’ – adapt to your match your configuration. Note that we added our user to two groups. The reason for this is a bit complicated, but it is important that the second group is the same as the groupname associated with /dev/ttyACM0 (from above).

After this is completed, you can restart the Arduino IDE and connect the Arduino to Chromebook. Under the settings menu, serial device you will find ‘/dev/ACM0’ is now enabled.

Arduino1Blink

If you pull up the demo sketch for blink, compile and install – and it should work. However we still have one more open issue that needs to be wrapped up.

One Dangling Detail – Fixing udevd

Our dangling detail is the fact that the Arduino IDE install created some association between the Arduino serial port (/dev/ttyACM0) and the dialout group as part of the install – but it is not working quite as expected. We can verify this by repeating the following:

cd /dev
ls -al tty*

Which produces the same information we have above with our /dev/ttyACM0 port in the serial group – not the dialout group. Now if we do this (from inside an Ubuntu Terminal):

sudo udevd --daemon
{disconnect / reconnect the Arduino Uno}
cd /dev
ls -al tty*

This produces a slightly different listing of which the line of interest will look something like:

crw-rw---- 1 root dialout 166,  0 Nov 26 05:37 ttyACM0

Which now shows that this device interface is associated with the dialout group. The reason for this is that the udevd daemon is a service that manages device configuration on most modern Linux systems. ChromeOS does not use udevd or even have it installed – for security reasons. The Arduino IDE creates some udevd rules (in the Ubuntu Chroot system) that map Arduino devices to the dialout group – but since the udevd daemon is not running in this crouton install – the rules are not applied until we manually started the daemon. We could manually start this each time we run our Ubuntu install, but the more correct and complete solution is add to udevd to the startup apps in ‘/etc/rc.local’. In Ubuntu, open a terminal and do the following:

sudo gedit /etc/rc.local

On the line before ‘exit 0’, add a new line with the following:

sudo udevd --daemon

Save and exit. What this does is, every time you boot your Ubuntu install, the udevd daemon will start – and all of the udev rules will be implemented. You can reboot, plug in the Arduino and confirm that it maps to the dialout group.

Wrapup

This is a  slightly messy install – since we had to get the udevd daemon started, and that would not be typical for an install. But overall this is nothing too far off the beaten path of Linux installations and maybe we learned something new in the process.

Update : 2013 Jan 27

The Cortado – https://launch.punchthrough.com/. Arduino compatible, Bluetooth programmable, onboard sensors, and long battery life. The Chromebook also has Bluetooth and it could likely function as a dev platform, and I would really like to try this on for size. The up to 100ft range and meshed networking – makes this a potential in the IoT space. [twolf]

Internet Security, Security, Uncategorized

Howto: Browse (more) Securely / Privately / Anonymously

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Background

For a number of reasons, many people are increasingly concerned with their privacy and security on the Internet. Since the primary reason most people use the Internet is for browsing, this would be a opportunistic use model to look for improvement. Of course the tradeoff is that as we make browsing more secure, we also may make the browsing experience more difficult. So in the list below, it progresses from low return / low impact to high impact / high return, and you can pick you pain threshold.

Note that in the context of a browser (and browsing), I define security as the ability to browse without being infected or compromised by malware. I define privacy as the ability to browse without sites (or other parties) tracking, harvesting information from my browser. Anonymity is when there is a sufficiently high degree of privacy that the browsing activity is anonymous – and true anonymity is not easy to achieve.

Off the Shelf / Good Browser Hygiene

Browser: There are lots of browser options and I cannot offer an opinion on most of them. On a regular basis browsers are reviewed for security – and Chrome, and Firefox are usually in the top three. Privacy is distinct from security, and generally Firefox rates higher than Chrome in that respect. However everything is a tradeoff, and I personally think that Chrome has better performance (which I may be imagining), and my Android devices and Chromebook are Chrome by design – so that is my browser choice by default. Secondary to that, I appreciate the rolling updates and aggressive stance Google takes on security, and I think that outweighs the weaker stance they take on privacy – since I believe I can manage my privacy / personal data easier than I manage security threats. Consider browser selection as the first thing to do in cleaning up your browser security / privacy concerns.

Browser Settings: The obvious things to check in your browser include:

  • Turn on “Do Not Track” / Open settings and search for this flag – if it is not set, set it. This provides some minimal and non necessarily mandatory level of tracking reduction.
  • Content Setttings (Cookies): I up the default level to “Keep local data only until I quit my browser” and “Block third-party cookies and site data”.
  • [Chrome Specific]Under Signin and Sync Settings, I encrypt my sync data with a passphrase. This is all about key management and reducing personal data on Google Servers.

Browser Plugins: The following list includes a few plugins that provide improved privacy.

  • HTTPS Everywhere: This is a plugin that will force a HTTPS connection as the default, with HTTP (non-secure) as the fallback.
  • DuckDuckGo Search: Duck Duck Go is a search service that provides much stronger statements about not tracking your browsing / searching activity (as compared with Google). They feel fairly strongly that this is a big deal. Take a look at their positions on results bubbling
  • DoNotTrackMe: A plugin that gives you explicit tracking information as you browse. This actually provides some visibility into what sites are tracking you in realtime.

Sites: What to do to reduce your browsing footprint.

  • Google Search History: By default Google saves your search history and used it to target ads and search results. My recommendation – turn it off.
  • Google Dashboard: A nice portal that provides a one view view into your data footprint on Google Servers. Review and clean it up. While you are there, setup an Alert on your name. It will give you any visibility into possible misuse of your name.
  • Twitter Privacy: Twitter by definition is fairly public so there is not much to tweak. However it makes sense to verify that “Do Not Track” is enabled and consider turning off / deleting location data.
  • Facebook: Expect this to change over time. Privacy settings seem to be a fast moving target at Facebook. So much of the business value proposition of Facebook is about eliminating privacy, so this will always be about providing some minimal level of privacy control that that is just enough to keep most users from leaving.

Overall these tweaks to your browsing experience will provide some improved level of security and privacy, but fundamentally much of the browsing process from your client system will still be relatively visible – the contents may protected with SSL/TLS, but where you are going, what you are downloading and how long you are there is not. Specifically, where you are going (page by page by page), how long you are there and how my kilobytes you have downloaded is all visible.  If your ISP / employer / campus / hotel / building has a proxy server between you and the Internet, they have access to this level of information.

Overall I consider these steps to just be good browser hygiene.

Some Better

If this level of exposure bothers you (it may), and you feel a need to mitigate this issue, read on – a VPN / proxy service may be the solution you are craving.

Technically a VPN and a proxy server are two very distinct functions. A VPN (Virtual Private Network) is a secure (i.e encrypted channel) and authenticated (i.e. username/password and server certificate) channel from your client system to some server on the Internet. In the enterprise / business world, VPNs are used to enable authorized users on the Internet access to corporate servers on the private networks. In the world of proxy servers, VPNs are used to provide a secure channel to some proxy server on the Internet.

A Proxy server is simply a relay for your Internet / Browsing traffic. You send some Internet request to the proxy server, and it redirects it to the Internet, with the source mapped back to the proxy server. When the response is received by the proxy server, it is then relayed back to your client system. Proxy servers are not explicitly secure, so they are generally coupled with some form of VPN to provide a secure channel.

There are large number of VPN/Proxy service providers around the world. For the most part, the free ones (reportedly) have a fairly high rate of malware infection and the for pay ones are from $40 to $100 a year. This is not an endorsement – but PureVPN and HideMyAss are both typical for-pay VPN/Proxy Services, with very typical pricing and functionality providing a wide range of target servers around the world.

When using a VPN/Proxy service, the net effect is that any geolocation will place you at (or near) the location of the proxy server. This means that if you are accessing some Internet service with geolocation service qualifiers (e.g. bbc.com, nfl.com) , you can appear to be somewhere that you are not. It also means that if your employer, hotel, campus, school has blocked sites/services, you can circumvent these restrictions with a VPN/proxy. In both of these cases you are not likely violating any laws, but you are likely violating some Terms of Service – implied or otherwise.

More legitimately, if you often use public or untrusted WiFi networks, a VPN / Proxy ensures that your traffic will not be sniffed on the local network. If you use WiFi in a high density environment, and are concerned about your network being compromised, or you don’t trust the other users on a shared network – a VPN/Proxy can ensure your traffic is secure / private even if your network may not be.

Ultimately, a VPN / Proxy service can provide a step up in privacy / security for a specific set of threats. However, by using a VPN / Proxy service you are literally handing this same information over the VPN/Proxy service provider – so if your concern is browsing/security in general, you have just shifted the risk.

More Better

From this point, there is one very obvious and better way to achieve better security/privacy – the TOR Browser. The TOR (The Onion Router) Browser is a custom version of Firefox packaged/integrated with a few tools related to The Onion Router, including an Onion Router proxy for your client system. The download package installs easily, and the TOR proxy starts automatically just be launching the TOR browser. If you are serious about using it for the privacy it can provide, read the Warnings FAQ.

The general principle behind TOR is that an outgoing datapacket is encrypted with some relay address on the TOR network, with multiple successive similar layers applied, and ultimately the packet is sent out to the network in which each one of the relays peels off the successive layers – and it is finally sent to the Internet destination. The goal / purpose of this effort is that through this obfuscated path, the user is much more anonymous and their privacy is protected.

In an ideal world, where TOR relays were spread around the world from different organizations it is possible to achieve some level of anonymity. In the real world, some of these relays are operated by agencies with the intent to compromise the TOR network, reducing the effectiveness. In addition some academic research has shown a few other weaknesses related to coordination between TOR relays. The net result is that the TOR network and the TOR browser provide a much high degree of anonymity than any other readily available solution – but it can be broken. For a recent example, refer to the story behind Silk Road shutdown. Details are lacking, but this does show it is susceptible if the incentive is high enough.

Bottom Line

There are a wide range of things you (as a user) can do to reduce your browsing footprint, reduce your ability to be tracked, increase your security and privacy (and anonymity). However, the first step to any of this is to assess what your threats are, and take reasonable steps to mitigate those threats. If you threats are non-specific and general, than it is likely that the non-specific and general browser hygiene solutions are sufficient. If you have specific threats that fit the more elaborate solutions, use appropriately.