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tsaitgaist, 02/19/2016 10:48 PM
udp sink


PageOutline = Osmocom SIMtrace =

Osmocom SIMtrace is a software and hardware system for passively tracing SIM-ME communication between the SIM card and the mobile phone.

It looks a bit like this: {{{
#!graphviz
digraph G{
//rankdir = LR;
Phone -> SIMtrace [label = "Flexi-PCB cable"];
SIMtrace -> SIM;
SIMtrace -> PC [label = "USB cable"];

SIMtrace [ label = "SIMtrace hardware" ];
}
}}}

When connected to a phone, it looks like this:

Image(simtrace_and_phone.jpg, align=center,50%)
Image(simtrace_functions.png, align=right,33%)

It works by utilizing the T=0 capable USART of the USB-attached AT91SAM7 microcontroller.

The USART passively receives the bytes as they are exchanged on the ISO 7816-3 / TS 11.11 interface between SIM and phone.
The received bytes are sent via USB to the PC, where a program called {{{simtrace}}} on the PC gathers data from the USB device,
parses the APDUs and forwards them via [wiki:GSMTAP] to the [wiki:wireshark] protocol analyzer.

Features * Completely passive scanner * RST and ATR detection * Auto-bauding with PPS / PTS support * Segmentation of APDUs TODO * Check for parity errors * Verify TCK / PCK check-bytes * Implement MITM Hardware

The first implementations used an Olimex SAM7-P64 development board with some of the I/O lines hooked up to the mechanical SIM card adapters from [wiki:RebelSIM_Scanner]. If the RebelSIM scanner is used, connect the USB even if just the lines are used. It needs to be powered, else the real reader will often fail to initialize the card.

Now we have a dedicated PCB design. The schematics and Gerber files are released as open source hardware and can be produced by everyone.

However, those of you who are not interested in building it from scratch can buy a complete factory-produced, tested and flashed PCB assembly from http://shop.sysmocom.de/products/simtrace

More details are available at [wiki:SIMtrace/Hardware]

Firmware

The firmware for the AT91SAM7S device was written by reusing a lot of the code for the [http://www.openpcd.org/ OpenPCD]
RFID reader. Details are available at [wiki:SIMtrace/Firmware].

Host PC Software

The {{{simtrace}}} program is part of the git://git.osmocom.org/simtrace.git repository. It will bind to the USB device
and send GSMTAP frames using UDP/IPv4 to localhost:4729.

=== Preconditions ===

[wiki:libosmocore] and headers (simtrace_usb.h) from the firmware.

additional packages : {{{
sudo apt-get install libusb-1.0-0-dev
}}}

=== Compiling it ===

{{{
git clone git://git.osmocom.org/simtrace.git
cd simtrace/host/
make
}}}

=== Accessing it ===

Add udev rules so to be able to use simtrace and access the device as non-root user (only need to be in the osmocom group)

{{{
sudo groupadd osmocom
sudo adduser $USERNAME osmocom
sudo tee /etc/udev/rules.d/10-osmocom.rules << EOF
  1. to use, install this file in /etc/udev/rules.d as 10-osmocom.rules
  2. rule to grant read/write access on SIMtrace to group named osmocom.
    ACTION=="add", BUS=="usb", SYSFS{idVendor}=="16c0", SYSFS{idProduct}=="0762", GROUP:="osmocom", MODE:="0660"
    EOF
    sudo service udev reload
    }}}

you must log out and back in so to take effect.

=== Using it ===

Simply start '''simtrace'''.
It will send the GSMTAP frames to UDP/IPv4 localhost:4729.

It will also print hexdumps of the frames to the console, looking like this: {{{
sudo ./simtrace
APDU: (9): a0 a4 00 00 02 6f 07 9f 0f
APDU: (22): a0 c0 00 00 0f 00 00 00 09 6f 07 04 00 15 00 15 01 02 00 00 91 78
APDU: (9): a0 a4 00 00 02 6f 38 9f 0f
APDU: (22): a0 c0 00 00 0f 00 00 00 09 6f 38 04 00 15 00 55 01 02 00 00 91 78
APDU: (16): a0 b0 00 00 09 ff 3f ff ff 00 00 3f 03 00 91 78
APDU: (9): a0 a4 00 00 02 6f ad 9f 0f
APDU: (8): a0 b0 00 00 01 00 91 78
APDU: (9): a0 a4 00 00 02 6f 07 9f 0f
APDU: (16): a0 b0 00 00 09 08 49 06 20 11 49 00 11 06 91 78
APDU: (9): a0 a4 00 00 02 6f 7e 9f 0f
APDU: (18): a0 b0 00 00 0b ff ff ff ff 64 f0 00 ff fe 00 03 91 78
APDU: (9): a0 a4 00 00 02 6f 78 9f 0f
APDU: (9): a0 b0 00 00 02 00 01 91 78
APDU: (9): a0 a4 00 00 02 6f 74 9f 0f
APDU: (23): a0 b0 00 00 10 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 91 78
APDU: (9): a0 a4 00 00 02 6f 20 9f 0f
APDU: (16): a0 b0 00 00 09 ff ff ff ff ff ff ff ff 07 91 78
APDU: (9): a0 a4 00 00 02 6f 30 9f 0f
APDU: (22): a0 c0 00 00 0f 00 00 00 f0 6f 30 04 00 11 00 55 01 02 00 00 91 78
}}}

Wireshark integration

There is an experimental patch, also part of the simtrace.git package. It is also included in the [wiki:wireshark] developer version (since wireshark 1.7.1).

To see the APDUs in wireshark: * on localhost SIMtrace automatically opens a UDP sink locally, no need to do any anything * to get the data on another machine * start an UDP sink for GSMTAP on the other machine (do not use netcat as it "connects" back) {{{
socat -u udp-recv:4729 /dev/null
}}} * tell SIMtrace on which machine to forward {{{
./simtrace -i 192.168.0.1
}}}

Image(wireshark-sim.png)

Protocol parsing is far from being complete, patches are always welcome!

Contact / Mailing List

For any development or usage related questions, there is a mailinglist [mailto:], you can subscribe/unsubscribe to it at http://lists.osmocom.org/mailman/listinfo/simtrace and read the archives at http://lists.osmocom.org/pipermail/simtrace/

Please kindly observe our [http://openbsc.osmocom.org/trac/wiki/MailingListRules Mailing List Rules]

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