The latest Yún shield's firmware should be "v2.0.5"
Model: Dragino v2 Version: Dragino-v2 common-2.0.5 Build Tue Jul 21 20:24:45 CST 2015
If you have early version like this:
Version: Dragino-v2 common-1.3.4 Build Sat Aug 2 17:35:47 CST 2014
It is time to upgrade.
Upgrading Using the Web Panel
Make sure the Yún shield and your computer are on the same network, and open a browser. Connect to the Yún shield's web panel page by entering the IP address.
Once logged in (default password:dragino), on the first page click upgade, on the upgrade page choose dragino2-yun-common-v2.0.5-squashfs-sysupgrade.bin at file system then click Upload buttom.
Upgrading Using the Command Line:
You can connect to the Yún shield via SSH and use a command line tool on your computer to upgrade the system's image.
To connect to your Yún via SSH, open the terminal application of your choice, and enter :
cd /tmp/ wget http://www.ibuyopenwrt.com/images/dragino2-yun-common-v2.0.5-squashfs-sysupgrade.bin
exec sysupgrade -n "/tmp/dragino2-yun-common-v2.0.5-squashfs-sysupgrade.bin"
Sending TERM to remaining processes ... sleep uhttpd dbus-daemon dnsmasq thd ntpd link_arduino_ww rcS logger syslogd klogd hotplug2 ubusd netifd Sending KILL to remaining processes ... uhttpd Switching to ramdisk... Performing system upgrade... Unlocking firmware ... Writing from to firmware ... [w] Upgrade completed Rebooting system...