Latest Iceweasel 42 user agents:

User Agent Platform Device
Mozilla/5.0 (X11; Linux x86_64; rv:42.0) Gecko/20100101 Firefox/42.0 Iceweasel/42.0 GNU/Linux Unknown
Mozilla/5.0 (X11; Linux i686; rv:42.0) Gecko/20100101 Firefox/42.0 Iceweasel/42.0 GNU/Linux Unknown
Mozilla/5.0 (X11; Linux i686 on x86_64; rv:42.0) Gecko/20100101 Firefox/42.0 Iceweasel/42.0 GNU/Linux Unknown