Skip to content

gr-gsm

GNU Radio blocks for receiving and analysing GSM signalling

What it does

Provides GNU Radio blocks and command-line tools for receiving GSM downlink signalling: finding a base station's control channel, demodulating it, and decoding the unencrypted signalling messages it carries.

Why you would want it

It is the standard teaching and research tool for how a cellular control channel actually works, and it is what most published cellular-security research builds on. It is receive-only and decodes signalling rather than call content.

Before it will work

GNU Radio and a receiver capable of covering the GSM bands -- typically an RTL-SDR with a corrected frequency offset, which grgsm_scanner will help establish. It is in the consent-gated rf-research profile, so installing it requires an affirmative answer that neither --yes nor a scripted install can supply on your behalf.

How it installs

  • apt: gr-gsm

Known problems

Frequency accuracy matters more than for most SDR software; an uncorrected RTL-SDR will fail to lock and produce nothing rather than an error. GSM deployment is being wound down in many places, so there may simply be no signal present. The package is built against a specific GNU Radio version and breaks when that version changes underneath it, which is the general problem D-017 defers all GNU Radio out-of-tree modules for.

Keeping it current

  • probe: apt policy
  • strategy: apt_upgrade

Source: catalog/packages/gr-gsm.yaml