Review of the UT-41 GPS, and a little about getting it to work with Kismet in BackTrack Linux

Review of the UT-41 GPS, and a little about getting it to work with Kismet in BackTrack Linux

Awhile back I was looking for a low cost GPS on Newegg.com to do some wardriving with. Being the cheap bastard that I am I did not want to pay more than $60 for it, and even most mouse type GPS units cost more than that. Unfortunately, NewEggs cheapest one was out of stock so I kept looking around. Eventually I found the UT-41 GPS on Geeks.com (see the links section at the bottom of this page). Hey, for $34.99 (about $42 after shipping) I was willing to give it a try seeing as it was about the cheapest GPS I could find (even if it did look like a black sperm). After doing a little online research I found that others had had some success getting it to work under Linux, and Linux compatibility was a must for me since I use Kismet (wardriving in Windows without monitor mode is like having sex with the lights off, you miss so much.). I'm happy to say it works fine, once I did some Googling around to figure out how to get it to work. As a service to the community, and to make a one stop search for the next person trying to get this GPS to work, here are my notes on getting the UT-41 running in Linux with Kismet. A lot of the info should be helpful users of other GPS models as well. What follows are my notes, first for Window, then Linux.

Windows XP/2000

The first thing I did when I got the GPS was try to get it working in Linux, but after a few problems I figured it would be best to troubleshoot it first by testing the unit in Windows. The Windows install was easy, it seems the UT-41 is just a GPS receiver and a Prolific 2303 serial to USB converter in one package. I installed the Windows drivers off the CD (the ones on Prolific's website work also), plugged in the GPS and it loaded just fine. After that I just had to determine what COM port it was on in Device Manager, then set my apps to use that port as a NMEA-0183 GPS.

I even got Earth Bridge to work with Google Earth. Giver Earth Bridge a shot if you use Windows, it's a fun little path tracking tool and it's free (Donation Ware at least). One bit of weirdness, under Windows my GPS seemed to work while I was indoors next to a south facing window, however in Linux I had to be outdoors. If anyone knows why, email me.

Linux (BackTrack and Kanotix)

It took me a bit of looking around to figure this out, but it's not hard. Most of my confusion was cause because I could get a LAT/LONG in Windows indoors, but I had to be outside with Linux. Here are the basic steps to get the UT-41 to work in Linux, along with a few trouble shooting commands.

Gpsd is the daemon Kismet and most other Linux apps use to talk to a GPS. In BackTrack I had to use these the following gpsd command to get it running:

gpsd /dev/tts/USB0

This device name is rather abnormal since in most Linux distros, including Kanotix, you use /dev/ttyUSB0 as your first serial USB device. After gpsd is started you can run Kismet. In BackTrak it's easiest just to use their config script:

start-kismet

After you run start-kismet it will ask you what WiFi device to use, and where to save the data. In other distros you will have to configure Kismet yourself. In Kanotix I had to edit my /etc/kismet/kismet.conf file and change two lines. First, the one that looks like:

source=madwifi_ag,wifi0,atheros

The above line is what I had to use for my SMC2336W-AG PCMCIA card, yours will most likely be different. Just look for the line in kismet.conf that starts with "source=" and change it accordingly. You will also want to find the line that starts with "gps=" and set it to true:

gps=true

once that's all done, you can just start Kismet as root. With a hard drive install of Kanotix you should be able to find your logs in "/var/log/kismet/".

Linux Trouble shooting

If your UT-41 is still giving you fits, try these trouble shooting commands:

See if the USB GPS is found:

root@bub:~# lsusb
Bus 001 Device 002: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port
Bus 001 Device 001: ID 0000:0000
root@bub:~#

You see from the above that it found the Prolific serial device.

Make sure that the GPS is connecting with gpsd by telneting to it and putting it in raw mode. Hitting enter by itself should just return the string "GPSD" but if you enter the "r" command you should get a stream of data that looks something like this if it is working:

root@bub:~# telnet localhost 2947
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.

GPSD

GPSD
r
GPSD,R=1
$GPGSV,3,2,12,17,47,258,,27,33,173,,24,16,189,,29,13,287,*74
$GPGSV,3,3,12,26,13,293,,19,05,056,,20,03,125,,04,02,199,*7A
$GPRMC,224206.00,V,3818.6285,N,08552.2345,W,,,200906,,,N*59
$GPGGA,224206.00,3818.6285,N,08552.2345,W,0,00,0.0,,M,,M,,*4F
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSV,3,1,12,31,73,296,,28,68,343,,08,59,189,,11,50,071,*74
$GPGSV,3,2,12,17,47,258,,27,33,173,,24,16,189,,29,13,287,*74
$GPGSV,3,3,12,26,13,293,,19,05,056,,20,03,125,,04,02,199,*7A
$GPRMC,224207.00,V,3818.6285,N,08552.2345,W,,,200906,,,N*58
$GPGGA,224207.00,3818.6285,N,08552.2345,W,0,00,0.0,,M,,M,,*4E
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
^]
telnet> quit
Connection closed.
root@bub:~#

You may also want to make sure that the pl2303 kernel module is loaded:

root@bub:~# lsmod | grep pl2303
pl2303 17924 0
usbserial 28392 1 pl2303
usbcore 106496 4 pl2303,usbserial,uhci_hcd
root@bub:~#

The following information about getting the UT-41 to work in Mac OS X comes from Jaku. Check out his forum post here: http://haxbyjaku.com/?p=38

I recently got a UT-41 at http://www.geeks.com/details.asp?invtid=UT-41&cat=GPS

It didn't support OS X out of the box so here is how I got it working.

First download the Serial to USB driver for OS X at http://www.apple.com/downloads/macosx/drivers/pl2303driver.html. After installing it, you are asked to reboot. Do so.

When you are back to OS X you can download and compile GSPd or get the GUI Binary gpsdXConfig at http://ghw.spade-men.com/gpsdx.html.

If you compiled GSPd, you can run the following command in terminal

gpsd tty.PL2303-0000103D

or if you are using the GUI you might have to refresh the serial list, and then select /dev/tty.PL2303-0000103D

To see if it is working, you can telnet to your localhost, press "r" and enter and you should see some GPS data like so.
telnet localhost 2947

Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.

GPSD

GPSD
r
GPSD,R=1
$GPGSV,3,2,12,17,47,258,,27,33,173,,24,16,189,,29,13,287,*74
$GPGSV,3,3,12,26,13,293,,19,05,056,,20,03,125,,04,02,199,*7A
$GPRMC,224206.00,V,3818.6285,N,08552.2345,W,,,200906,,,N*59
$GPGGA,224206.00,3818.6285,N,08552.2345,W,0,00,0.0,,M,,M,,*4F
$GPGSA,A,1,,,,,,,,,,,,,,,*1E

After that you can select GPS under Preferences, and choose GPSd in the drop down. After words you should have GPS working in OS X with the UT-41.

Closing

That should about cover it. All in all, I can't complain about the UT-41 for the price. I'm sure there are a lot better GPS units out there, but with it's magnetic base, Linux compatibility and low price I'd have to recommend it for folks just getting into wardriving who don't want to spend a lot of cash.

If you want to know more about wardriving tools in general check out the following videos:

Basic Tools for Wardriving
Infonomicon TV Ep 7 The RFMon section

Enjoy.

Links:

UT-41 GPS at Geeks.com
http://www.geeks.com/details.asp?invtid=UT-41&cpc=SCH

UT-41 GPS at Geeks.com via Amazon (which I may or may not get referral fees for, hey, I'm a whore)
http://www.amazon.com/12-Channel-NMEA-0183-GPS-Receiver-UT-41/dp/B000G6TYC8

Google Earth
http://earth.google.com/

Earth Bridge
http://mboffin.com/earthbridge/

NetStumbler
http://www.netstumbler.com/

Kismet
http://www.kismetwireless.net/

GPSD
http://gpsd.berlios.de/

BackTrack Boot CD
http://www.remote-exploit.org/index.php/BackTrack

Kanotix Linux
http://kanotix.com/