Sjur Usken

Views on new technologies and business opportunities from Sjur Usken

Monthly Archives: May 2009

Cain&Abel provides support for MitM attack on SIP TLS


I started using Cain&Abel for so many years ago for analyzing and troubleshoot WLAN. It has rich support for different WLAN protocols and also general network protocols. Visiting their webpage today, reveals that they are definitely keeping the speed up on the updates, especially on VoIP. From www.oxid.it

Cain & Abel v4.9.31 released

  • SIPS Man-in-the-Middle Sniffer (TCP port 5061; successfully tested with Microsoft Office Communicator with chained certificates).
  • Added support for RTP G726-64WB codec (Wengo speex replacement ) in VoIP sniffer.
  • X509 certificate’s extensions are now preserved in chained fake certificates generated by Certificate Collector.
  • Extended ASCII characters support for SSID in Passive Wireless Scanner.

This tool makes “The Man in the Middle” attack easy. Redirect the DNS address for a SIP Server to this tool, then proxy the traffic to the right server. You will gather all passwords for all clients “passing by”. So,  always, always use proper signed certificates on your servers. The VoIP client (SIP UA) should not (easily) accept connections from a SIP TLS server where the certificate can not be validated.

Older release news are interested for those handling the Microsoft OCS:

  • Added support for the following codecs in VoIP sniffer: G722, Speex-16Khz, Speex-32Khz, AMR-NB, AMR-WB.
  • Added SIREN codec support in VoIP sniffer (the default one used by Windows Messenger).  (from 207…)

Cain&Abel is an excellent tool for debugging voice problems in the full HD voip world as well now!
Thanks to MAO in Oxid for providing this great tool!
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The Linux Media Center Solution! Awesome!


Browsed through the Internet for the Freedom Fone Project and came over the LinuxMCE. I have been dreaming about a project like this, and was really amazed about the possibilities included already.
They have done a smart thing dividing it up in two parts;

  • one powerful core server for doing encoding of incoming media
  • one or more clients connected to each screen around in the house.

Some of the features:

  • Surveillance camera
  • Intrusion alarm
  • Heat/Cooling control
  • Lightning control
  • Full media center functionality
  • Telephone central

All these features are knit together into a nice user interface where you only need a remote with three (3) buttons  (+ OK and cancel) to operate. And it’s even cooler with a gyro remote control (anyone played with the Nintendo wii??)

What I’m missing for my immediate use:

  • heat control for radiators (a small motor to turn the knob..)
  • interface to my proprietary doorphone. (can probably be done with a Cisco/Linksys SPA3100 ATA)

I have already e-mailed several of my friends who are looking for this and will definely spread the word!

When it is also running on the Asus EEE Top (15,6″ touch screen and can do full HD video) it will be great! Or the even better MSI Wind Top EA 1900 (who makes these names by the way…)

Keep up the good work! The future will be fantastic!
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The Freedom Fone Project for Africa!


There are not much publicity about this project, so I wanted to explain what it’s all about.The ultimate goal is to make it easy to spread information e.g. people send a SMS and get a call informing them about HIV/AIDS or the weather.

The Freedom Fone is a universal media conveyor, it should take most media input from people (mobile, skype, web, e-mail) and generate output (sms, call, radio, web) in the best possible way.

The limitations are the usual one in Africa. No power, little or no Internet connection, few people to run it, harsh environmental conditions, etc…

Our solution seems easy, but there is some work behind it. Take a standard netbook (asus preferred) and plug in a USB to cellphone (mobigater). Install Ubuntu with Freeswitch and several other tools. Glue it all together with a lot of customization, and BINGO! We have a Freedom Fone Server!

Usage scenarios

An organization wants to spread information about specific topics. We create a SMS word people can send to be called back and informed.

Farmers want to know about the weather and subscribes on a daily or weekly weather forecast.

Ex.pats living abroad wants to help out and makes an informative radio program. This is aired on the local radio station

Others? Please comment!
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And test from the Snom phone…


The snom phone seems to have a built-in brute-force blocker. After a short while it does not even allow me into the web interface. This is a good idea, but can also be misused as a Denial-of-Service (DoS) attack.
Will write more about this phone when I have time.