Latest Iceweasel 23 user agents:

User Agent Platform Device
Mozilla/5.0 (X11; Linux x86_64; rv:23.0) Gecko/20130621 Firefox/23.0 Iceweasel/23.0a2 GNU/Linux Unknown
Mozilla/5.0 (X11; Linux i686; rv:23.0) Gecko/20100101 Firefox/23.0 Iceweasel/23.0.1 GNU/Linux Unknown
Mozilla/5.0 (X11; Linux i686; rv:23.0) Gecko/20100101 Firefox/23.0 Iceweasel/23.0 GNU/Linux Unknown
Mozilla/5.0 (X11; Linux i686 on x86_64; rv:23.0) Gecko/20100101 Firefox/23.0 Iceweasel/23.0 GNU/Linux Unknown