This Thursday the 19th, we have another installment of the Software Defined Radio (SDR) workshop. The goal of which is to provide introductory support to people learning about SDR’s as well as let some of the more seasoned folk work on their projects. We’ve talk to a lot of people lately about what an SDR is and why we have a workshop for it so I thought I’d review why they’re fun.
What is an SDR?
Unlike some radio equipment which only provides a small range of frequencies you can transmit and receive on, SDR’s let you use a single device, and control their frequency from very low (<100Mhz) to very high (2.4GHz+).
In the past, if you wanted to listen in on a certain frequency, say your garage door opener for example, you’d have to buy a piece of hardware that runs at that frequency — in this case it’s often 434MHz. Now for as little as $20, you can buy a device that can read your garage door opener at 433Mhz, listen to the local FM radio station at 90.5Mhz, or track airplanes at 1090Mhz. This lets you play with different frequencies and see what’s being transmitted. You may be surprised.
This also lets you learn about the basics of RF: electronics, antennas, ways to decode a signal.
The workshop is open to the public; non-members are welcome as always. Feel free to drop a comment on the meetup page if you’re interested but have some questions.
SDR Workshop on Meetup
from antitree on February 17th, 20150 Comments
The JTAGulator is a tool designed by Joe Grand – the guy that used to make the DEFCON badges for years and was part of one of the first hackerspaces, Lopht. He did a Blackhat LV presentation on his newest open hardware, open source project called the JTAGulator. It’s purpose is to help you figure out the pins of a JTAG or UART device. This is normally an annoying and time consuming process.
JTAG (Joint Test Action Group) is just a name for a standard way of providing a debug interface to your hardware devices. What’s nice about it is with one interface, you can provide debugging capabilities to a variety of chips on your board. So if you have two microcontrollers, each of them can be separately accessed through one interface. Pretty cool.
Hackers have been using JTAG for years to reverse hardware. You might have seen them used when messing with router firmware to install DD-WRT or OpenWRT. For WRT supported routers, JTAG often gives you the ability to push a custom firmware onto a board or extra the firmware that is currently installed.
JTAG For Security
Of course with all of my projects, I add a security twist. JTAG lets me gain low level access to a device and see how it works. An interface may be able to dump an EEPROM which could contain the cryptographic keys that are securing another piece of memory on the chip. Or it could give me a serial console similar to a root terminal that lets me interact with a device like a computer. The point is, it’s a debuggable interface that I can use to exploit in a variety of ways to learn about how the device works.
You might wonder why these interfaces even exist on hardware since they give hackers the opportunity to access your hardware. Because JTAG is so useful for debugging, manufacturers actually use this interface the same way you would, to make sure the device is functioning properly. That’s why it’s highly likely you’ll find some kind of debug interface for your boards.
The JTAGulator connects to your computer using a micro-USB cable that shows up as a serial device. In Linux, that device will be something like /dev/ttyUSB0. It uses 115.2K baud 8N1. Once connected using something like minicom or gtkterm in Linux, you’ll see a prompt of available options. You can now start JTAGulating.
To connect the JTAGulator to a device, the board is designed to use the cables from a standard Bus Pirate board. You can either do that, or just use some aligator clips to connect to the pins. Either way, the board you’re working on is going to need to be have the JTAG leads broken out so you can connect something to them. In my little Asus router that I found, these pins are pretty easy to access. I just soldered some cables on to them, and added a bit of glue to make sure they kept.
Asus Router with wires near JTAG leads
From this point, your router should be connected to the JTAGulator, your JTAGulator connected to your computer, and you should have a console interface waiting for directions.
The first step is to set the voltage. It has a range of 1.2 to 3.3V and this is going to be important for you to figure out before hand. (If you don’t know how to figure out the voltage on your board, you can probably ask someone at Interlock to show you using a multimeter.) Then you can choose how you’d like to scan for JTAG. There are two options, one is more thorough and time consuming but I don’t have enough data to tell you which is better for which situation (feel free to chime in if you know). Either one will prompt you for which pins you’d like to test with, which should correspond to the pins you’ve connected on your JTAGulator. When you run it, it will attempt every possible combination of pins until it thinks it has found the right one. It also has a UART discovery mode.
This is not the first JTAG discovery product out there but it’s the first I’ve used. I mentioned that the project is open source so here is a link to Joe’s site to help you build your own board if you want, or if you’re like me, you can buy them from a company like Adafruit, too.
from antitree on October 16th, 20130 Comments
This weekend, Interlock participated in two milestone events: Our third annual meeting, which we’ll talk about in another post, and one of our members getting married. Walter (N2VBP) and Cheryl have finally tied the knot to make it official.
Attendees were friends and family of the couple including Walter ‘s daughters who he setup on Skype to stream the wedding live. Our resident video podcaster Radical Geek recorded the ceremony and I, with my newly acquired credentials from the Universal Life Church Monastery that I signed up for on the Internet, solemnized the wedding.
Brian, also decided to do a 3D sculpture of the Walter and Cheryl so he took a bunch of pictures as they held hands. With the help of some software, he’ll be able to turn them into a 3D model and hopefully print them out so they look like cake toppers. Congratulations guys!
from antitree on December 17th, 20120 Comments