Linux Microsoft Skype For Business Lync 2013 Client

Posted in: technology. Tagged: linux, ubuntu, microsoft, skype, lync

I was surprised to learn that Ubuntu 14.04 can talk to Skype for Business AKA Lync 2013 using the Pidgin Instant Messaging client. The general steps were:

# apt-get install pidgin pidgin-sipe

And then restart Pidgin and add a new Account. The Office Communicator is the relevant plugin, with the following parameters:

• Protocol: Office Communicator
• Username: Your Office 365 or Skype for Business username - probably your email address
• Password: Your password is obviously required - and will be stored unencrypted in the config file, so you may wish to leave this blank and enter at each login
• Server[:Port]: Leave empty if your set-up has autodiscovery
• Connection type: Auto
• User Agent: UCCAPI/15.0.4420.1017 OC/15.0.4420.1017
• Authentication scheme: TLS-DSK

I am unclear why the user agent is required, and whether that will need to change from time to time or not. So far it has worked fine here.

Unfortunately a few days ago the above set-up stopped working, with “Failed to authenticate with server”. It seems that you must now use version 1.20 of the Sipe plugin, which fixes “Office365 rejects RC4 in TLS-DSK”. As this version was only completed three days ago, it is not yet available in any of the Ubuntu repositories that I have been able to find, you will probably have to compile yourself.

Broadly speaking I followed these key stages:

1. Install build tools if you don’t already have them:

   sudo apt-get install build-essential

2. Install checkinstall if you don’t already have it:

   sudo apt-get install checkinstall

3. Download source files.

4. Extract source:

   tar -xvvzf pidgin-sipe-1.20.1.tar.gz

5. Change into source directory:

   cd pidgin-sipe-1.20.1

6. Read carefully the README file in the source directory.

7. Install dependencies listed in the README:

   # apt-get install libpurple-dev libtool intltool pkg-config libglib2.0-dev libxml2-dev libnss3-dev libssl-dev libkrb5-dev libnice-dev libgstreamer0.10-dev

These dependencies may change over time, and your particular requirements may be different from mine, so please read the README and that information should take precedence.

Lastly, as an ordinary user, you should now be able to compile. If it fails at any stage, simply read the error and install the missed dependency.

$ ./configure --prefix=/usr
$ make
$ sudo checkinstall

I found checkinstall was pre-populated with sensible settings, and I was able to continue without making any changes. Once complete a Debian package will have been created in the current directory, but it will have already been installed for you.

For some reason I found that at this stage Pidgin would no longer run, as it was now named /usr/bin/pidgin.orig instead of /usr/bin/pidgin, I tried removing and reinstalling pidgin but to no avail. In the end I created a symlink (ln -s /usr/bin/pidgin.orig /usr/bin/pidgin), but you should not do this unless you experience the same issue. If you know the reason for this I would be delighted to receive your feedback, as this isn’t a problem that I have come across before.

Restarting Pidgin and the Office Communicator sprung into life once more. Sadly I would imagine that this won’t be the last time this plugin will break, such are the vagaries of connecting to closed proprietary networks.