Examples: RTPEngine speech

Speech Recognition

HOMER + OpenSIPS + RTPEngine

What if we could "read" users conversations directly in HOMER next to traces? Well, we can!

Speech recognition for VoIP has been around for ages, and the recent storm of speech recognition services keep this an evergreen subject to hack around with. In this guide, we'll assemble one of the many possible sets to create an "intercepting" SIP+RTP Proxy able to post-process recorded calls and correlate them for fun and profit.

HOW?

The latest RTPEngine release features recording capabilities via a new set of dedicated flags/options and recording commands we can directly control from an OpenSIPS dialplan:

  --recording-dir=FILE             Spool directory where PCAP call recording data goes
  --recording-method=pcap|proc     Strategy for call recording
  --recording-format=raw|eth       PCAP file format for recorded calls.

In this experiment, we'll leverage this new feature to emulate and extend a Sip:Wise dangerous demo on the same subject and attempt to:

Record Complete Calls through our proxy (intercept?)
Post-Process Recordings for Speech Recognition
Send any results in HEP format to HOMER

Setup

The ingredients of our intercepting recipe:

OpenSIPS 2.x
RTPEngine 6.x
NodeJS + our demo application
A free BING Speech API Key

Lazy Mode 100

Good news! We prepared a full working docker container with all of the elements required for this demo!
Bad News! You're going to build this locally to match your kernel version (unless you're on 3.16.0)

Docker Everything!

For the sake of simplicity, we'll use a container running OpenSIPS + RTPEngine recorder with open relay settings, thus able to proxy SIP towards any target system of choice - in other words, we will use a real SIP account on the other end.

1: Building from Source

In order for RTPEngine to insert and use its kernel recording modules on a given Docker system, the container must be built for the specific underlying OS kernel version - since we're at it, we'll build everything from sources! Mind this might fail when using "virtualized" Docker flavours (Virtuozzo, etc)

Make sure Docker is installed, and proceed to build your container:

git clone -b dev https://github.com/lmangani/docker-rtpagent-speech
cd docker-rtpagent-speech
docker build -t qxip/docker-rtpengine-speech .

NOTE: If you're running on Debian 8 with kernel 3.16.0-4 you can use the master repository and the prebuilt packages

2: Configuring the Stack

The repository ships with a sample docker-compose file ready to be customized with our parameters. Adjust the port range parameters to your likes, and enter the details of your HOMER installation:

version: '2.2'
services:
  opensips-rec:
    image: qxip/docker-rtpengine-speech
    privileged: true
    restart: always
    environment:
      ADVERTISED_RANGE_FIRST: 20000
      ADVERTISED_RANGE_LAST: 20100
      HOMER_SERVER: 'YOUR_HOMER_IP'
      HOMER_PORT: 9060
      BING_KEY: 'YOUR_KEY_HERE'
    volumes:
       - /var/lib/mysql
       - /recording
    ports:
      - "5060:5060/udp"
      - "5061:5061/tcp"
      - "20000-20100:20000-20100/udp"
  captagent:
    container_name: captagent
    image: qxip/captagent-docker
    network_mode: "service:[opensips-rec]"
    environment:
      - ETHERNET_DEV=any
      - CAPTURE_HOST='YOUR_HOMER_IP'
      - CAPTURE_PORT=9060

Once you're happy with the settings, launch the container set:

docker-compose up -d

2: Make a Call!

This is the easy part. Configure your existing SIP account to proxy through your shiny new Proxy. With a bit of luck you'll get REGISTERED - Next, make a call to your voicemail, yourself or a talkingh clock (no screaming monkeys for this one tho)

Keep things short for simplicity, maybe add a few breaks between sentences, and hangup!

3: Check for Results

The call recordings will be picked up and processed within 30s from hangup by the built in nodejs app.

Allow some time for this process to take place (you can watch syslog inside the container for actin) and then proceed to locate your call session in HOMER or HEPIC - If things went right, a few log entries should magically appear, revealing your conversation (or at least, what Bing Speech made of it!)

Did it work? Share your results with us or shout out @sipcapture on twitter!