Monday, 6 June 2016

FreeSWITCH - Check what configuration directories are in use

There is a little trick to see what directories FreeSWITCH is using as paths for the configuration files:

/opt/freeswitch/bin/fs_cli -x 'global_getvar'| grep _dir

For example, the output can be:


This is handy in particular when you're testing an installation from source but the configuration is not in the default location.

It's possible to set non-default values by passing them as arguments for the daemon, e.g.:

/usr/local/freeswitch/bin/freeswitch -conf /opt/freeswitch/etc/freeswitch/ -log /usr/local/freeswitch/log -db /usr/local/freeswitch/db -ncwait -core

In general, when in doubt about the configuration path, use that fs_cli command to verify.

More info is as usual available from FreeSWITCH official documentation: Command Line Switches.

Friday, 27 May 2016

Continuous Integration and Kamailio

I've presented a workshop at Kamailio World 2016. It focused on tools to help automating the build, deployment and test of Kamailio-based applications using Jenkins, Docker and a few other technologies.

It's been also an opportunity to show a sample usage of the new http_async_client module, designed to perform non-blocking HTTP queries from Kamailio.

The interested reader can find the slides here:

And if you have an hour to spare, here's the full video:

Any feedback or question you may have, please get in touch. I have a post on the event in progress, but there are so many things to highlight that it will require some more time.

Many thanks to Daniel and Elena-Ramona (more info here), event hosts, and for video streaming, recording and editing.

Wednesday, 3 February 2016

Extracting Opus from a pcap file into an audible wav

From time to time I need to verify that the audio inside a trace is as expected. Not much in terms of quality, but more often content and duration.

A few years ago I wrote a small program to transform a pcap into a wav file - the codec in use was SILK.

These days I'm dealing with Opus, and I have to say things are greatly simplified, in particular if you consider opus-tools, a set of utilities to handle opus files and traces.

One of those tools, opusrtp, can do live captures and write the interpreted payload into a .opus file.
Still, what I needed was to achieve the same result but from a pcap already existing, i.e. "offline".

So I come up with a small - quite shamlessly copy&pasted - patch to opusrtc, which is now in this fork.
Once you have a pcap with an RTP stream with opus (say in input.pcap) you can retrieve the .opus equivalent (in rtpdump.opus) with:

./opusrtp --extract input.pcap

Then you can generate an audible wav file with:

./opusdec --rate 8000 rtpdump.opus output.wav

Happy decoding.

Friday, 18 December 2015

TADHack mini Paris

"I’ve been following TADHack and its related events for some time, and finally this month I got the opportunity to attend TADHack-mini Paris. Participants can join from remote too, but the personal full immersion is something different (even, ironically, when the topic is Real Time Communications, and more in particular WebRTC and Telecom APIs.
We met in central Paris [...] "
This is the beginning of the behind-the-scenes story about my TADHack participation. You can read my full article here.

Wednesday, 16 December 2015

Speed up testing Kamailio routing

I was very happy to see the news of the release of a new Kamailio module, authored by Victor Sveva.
CFGT can be used to test call scenarios and see what routing logic was triggered in Kamailio.
Test calls need to be marked with a specific, configurable Call-ID pattern ('callid_prefix').
A JSON report is generated, with the possibility to choose what variables to dump into it.
This is going to greatly simplify testing, while potentially keep the logging to a minimum. Highly recommended.

Wednesday, 25 November 2015

Docker and Puppet for Continuous Integration

This is a topic I really care about. Please take a look at the slides (they are quite verbose) used in a seminar at a local developers group:

Thursday, 15 October 2015

Building git 2.6 and enabling TLS 1.2 on CentOS 7

There are scenarios where TLS 1.2 is not just enabled, but the only one accepted.
In these cases many clients fail to connect over HTTPS.
I needed to be able to use 'git clone https://...' on CentOS 7, and since it was failing and I spent some time on a work around, I'm sharing it here.

The system is a CentOS 7 host on DigitalOcean, with kernel

Linux 3.10.0-123.8.1.el7.x86_64

git is 1.8.3, the stock version
nss is 3.19.1-5.el7_1

If I do something like

curl  --tlsv1.2

the connection is successful, but a command like

GIT_CURL_VERBOSE=1 git clone

was giving a connection error with this code:

( only accepts TLSv1.2).

Long story short, I read somewhere that git 2.6 had support for configuring TLSv1.2, and I downloaded the source code of git 2.6.0 from

Built, installed, added to my .gitconfig this:

sslVersion = tlsv1.2

but no cigar.

So I dug in the code and commented out a dependency for a version of libcurl in http.c (I'm commenting out the #if - #endif):

  //GV#if LIBCURL_VERSION_NUM >= 0x072200           { "tlsv1.0", CURL_SSLVERSION_TLSv1_0 },           { "tlsv1.1", CURL_SSLVERSION_TLSv1_1 },           { "tlsv1.2", CURL_SSLVERSION_TLSv1_2 }, 

Rebuilt and reinstalled, and this time it worked fine.