The version of sssd (1.9.1) shipped with default Ubuntu 12.10 is broken. It fails while communicating with ldap server over StartTLS. In order to make it work it has to be updated to the latest stable version 1.9.4 (at the time of writing) either from the source
https://fedorahosted.org/sssd/ or an easier approach would be to download from ppa:
sudo nano /etc/apt/sources.list
add the following ppa to the sources.list
deb http://ppa.launchpad.net/sssd/updates/ubuntu quantal main deb-src http://ppa.launchpad.net/sssd/updates/ubuntu quantal main
and then do an update and install
sudo aptitude update
sudo aptitude install sssd
