This application parses diagnostic messages of Qualcomm and Samsung baseband through USB, and generates a stream of GSMTAP packet containing cellular control plane messages.
Only tested in Linux, mostly various versions of Ubuntu. Python 3 is a minimum requirement, and the following external modules are required:
To properly decode GSMTAP packets generated by SCAT, Wireshark 2.6.0 or above is required. For older Wireshark releases, we are providing a Wireshark Lua plugin to extend the GSMTAP dissector. GSMTAP definition used by SCAT is based on libosmocore 0.11.0. Note that SCAT itself is not depending on the libosmocore.
Cellular device must expost the diagnostic port via USB. This is largely
device-dependent and we can not give generic solution for all devices. Search
the Internet with keyword (your device name) qpst to get the method of
exposing the diagnostic port for Qualcomm-based smartphones. You may refer to
the wiki page for instructions on
how to opening the diagnostic port through USB on some devices.
If your smartphone does not expose the diagnostic port via USB, you can try using the baseband dump features existing in some smartphones. Follow the wiki page for details.
Install SCAT through pip using:
# If you want fast CRC calculation (for Qualcomm and HiSilicon)
$ pip install "scat[fastcrc] @ git+https://github.com/fgsect/scat"
# If you don't want or can't build libscrc
$ pip install git+https://github.com/fgsect/scat
Please note that the name SCAT is taken in the PyPI, I will find further solution.
For development purposes, please use pip install -e .[fastcrc] or pip install -e . on your checkout directory.
The older scat.py is moved to src/scat/main.py.
While we recommend using USB directly to access the diagnostics port, if your
smartphone's or cellular module's diagnostic port is accessible via serial port,
using it is also possible. The qcserial and option kernel module do not have
the information of diagnostic port of all Qualcomm-based smartphones and
cellular modules, and no such module exist for Samsung-based smartphones.
By default, SCAT will send packets to 127.0.0.1, control plane packets to UDP port 4729 as GSMTAP, user plane packets to UDP port 47290 as IP.
Exit the application with Ctrl+C.
Please see the wiki page for advanced options.
-t option specifies the type of baseband. Following options are available:
-t qc: Qualcomm-t sec: Samsung-t hisi: HiSilicon (experimental, only baseband dump is supported)
If one of the following packets are not properly decoded on Samsung baseband
please file an issue with the debug output (--debug) attached:
- HSPA UL1 RF Info
- LTE PHY Cell Info
- LTE RRC Serving Cell
SCAT version up to 1.1.0 required specifying the Samsung baseband type manually
using -m. As SCAT now autodetects the Samsung baseband type, for SCAT 1.2.0
and above this option is only required when analyzing the raw SDM file without
start response.
Accessing the baseband diagnostics via USB:
$ scat -t qc -u -a 001:010 -i 2
$ scat -t sec -u -a 001:010 -i 2
Although there are small heuristic to determine the connected device, it is
recommended to explicitly specify the USB device address and interface number of
diagnostics node. -a 001:010 specifies the address, which follows the same
syntax visible in lsusb command. -i 2 specifies the interface number of the
diagnostic node, which is again device specific.
Newer Samsung devices require a correct magic number to be supplied to start the diagnostic session through USB. Please see Issue #27 for more information on this.
Accessing the baseband diagnostics via serial port:
$ scat -t qc -s /dev/ttyUSB0
Replace /dev/ttyUSB0 to what is your diagnostic device.
Parsing the baseband dump file:
$ scat -t qc -d test.qmdl
$ scat -t sec -d test.sdm
$ scat -t hisi -d test.lpd
Please see the wiki page.
Issues related to exposing the diagnostics port via USB is out of scope.
- On certain Qualcomm devices, after exiting and launching the application for more than once, initialization eventually hangs and no messages are appearing. Root cause still in investigation. Solution: reboot the smartphone.
SCAT is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
We are kindly asking any academic works utilizing and/or incorporating this software to cite one of these references listed below:
- Byeongdo Hong, Shinjo Park, Hongil Kim, Dongkwan Kim, Hyunwook Hong, Hyunwoo Choi, Jean-Pierre Seifert, Sung-Ju Lee, Yongdae Kim. Peeking over the Cellular Walled Gardens - A Method for Closed Network Diagnosis -. IEEE Transactions on Mobile Computing, February 2018.
Thanks to Christian Oschwald and Willem Hengeveld from GSMK for their support on Samsung SDM parser.