function sha256sum() {
    python -sBc "import hashlib;print hashlib.sha256(open('$1','rb').read()).hexdigest()"
}

echo -e "Update Available. Install will begin in 15 seconds...\n\n"
echo -e "All local LAN Turtle data will be erased.\n\n"
echo -e "Press CTRL+C to CANCEL\n\n"
sleep 15
echo -e "Downloading Upgrade file, please wait.\n\n"
wget -q -O /tmp/upgrade.bin https://downloads.hak5.org/api/devices/lanturtle/firmwares/6.1
echo -e "Upgrade file downloaded. Verifying file integrity.\n\n"
[[ "$(sha256sum /tmp/upgrade.bin)" == "e8af71827f0c98fc1e62b531e2f0e4dbad12c1e45738affd6aaeedc92142af76" ]] && {
        echo -e "DO NOT UNPLUG OR POWER DOWN THE LAN TURTLE\n\n"
        echo -e "Upgrade in progress. Please wait ~5 minutes.\n"
        echo -e "The LAN Turtle will reboot when the upgrade is complete.\n"
        echo -e "This SSH session will now close.\n"
        echo "sleep 10 && sysupgrade -n /tmp/upgrade.bin" | at now &> /dev/null
        sleep 8 && clear
        killall sshd
} || {
        echo -e "SHA256 checksum missmatch. Please try again."
}