Default [FAQ] Root Mini-FAQ: What's the big deal with root?

This topic deals specifically with root accessbility. For other topics, please consult the Chromecast FAQ thread or Search.

Are all Chromecasts rootable?
NO! Only those shipped with the original vulnerable bootloader (build 12072) can be rooted. See the Rootable Serial Numbers thread for guidance.


Root now or root later? Why do I need to root before setting up and using the device?
THERE IS NO OPTION TO ROOT LATER!
Short of finding a new root method, the bootloader is the only way to write to the device and therefore change the filesystem, which is what is necessary for injecting root.
Google's OTA update will update the bootloader and patch the vulnerability FlashCast uses to be able to write to the device and get root and disable Google OTAs so the hole does not get patched.


Do I even need root?
Initially there were more reasons to root, like the ability to send local files to Chromecast. However, new Google-approved apps like Avia, RealPlayer Cloud and Plex were released to bridge that gap.
So right now, functionality-wise, root brings you Eureka-ROM.
Eureka-ROM brings you...
  • Custom whitelist (run apps not whitelisted/approved by Google)
  • DHCP client control (use static address)
  • DNS control (use non-Google DNS)
  • Status (temperature reporting, IP, firmware)
  • ADB on/off
  • Telnet on/off
  • SSH on/off
Likely more will come in the future.
DNS control is important for people using Chromecast outside of the US, as many of the Chromecast services like Netflix and Hulu Plus are either unavailable or have restrictions on available content in other countries.


Why can't we get root another way?
While I'm not one to say never, because there are a lot of clever people out there but...
Unlike phones and tablets, Chromecast is quite the ornery Android device...
  1. It has no Fastboot.
    So we can't download a new ROM image that way.
  2. It has no accessible recovery.
    So we can't install stuff or access the filesystem with an update.zip
  3. It has no image loader/flasher utility.
    So we can't download a new ROM image that way either.
  4. It has no interface (screen or input device).
    This just makes it even more difficult to interact with it for hacking purposes.
  5. ADB, Telnet and SSH are disabled by default.
    No ways to peek or poke around there either.
  6. The runtime filesystem is read-only.
    So a clever app can't make changes either.
  7. Google OTA updates are automatically downloaded and applied, updating the bootloader and ROM. Updated bootloader versions will only execute Google-signed code.
    So once you get a Google OTA update, you lose the ability to update the ROM (without a new root method).
Long story short, to get root you need to access the filesystem or execute custom (not signed by Google) code.
But you can't access the filesystem.
And you can only execute custom code on the original bootloader (build 12072).
Perhaps, once the SDK is released, we could see some kind of permissions exploit that could allow a clever app to somehow obtain root access to update the system or write a vulnerable bootloader, but that remains to be seen.


I had root with Eureka-ROM and now it appears I don't?
This can happen if the power is pulled or lost during an update.
You may still have the vulnerable bootloader and be able to get root back, depending on how long it has been since the attempted update.
Unplug Chromecast from power until you can re-flash the newest Eureka-ROM via OTG.
This is a good reason to use AC/wall power rather than USB on the TV, as the TV often cuts USB power when the TV is turned off.
For further details, see this post.


Well that pisses me off! Google is evil! I deserve root!! I'm buying something else!!!
Google never promised root. They just promised an SDK that was released February 3, 2014 here. Root capability just came as an unexpected (and perhaps unintended) gift for initial units.
Chromecast is not a phone or tablet. It's a $35 appliance to be connected to a TV. Hacking your TV might be fun, but Chromecast is not aimed at hackers. It's aimed at the normal people who just want to get Netflix, YouTube, etc on their TV and people who like the concept of using the Android or iOS device instead of adding yet another remote control to their pile.
Whether you buy Chromecast is your choice. Nobody said you had to buy every new device Google puts out. Google isn't Apple.
Also keep in mind, Chromecast is useless without content, which requires content providers. Content providers don't like the concept of root access to a device that plays their content. They fear it will allow their content to easily be pirated. That's why CinemaNow and other services don't allow rooted devices.
For the longevity of the device and continued usability for normal customers, it's in Google's best interest not to have widespread/publicized hacking of Chromecast. Long story short, even with thousands of rooted Chromecasts, we're still a minority compared to the millions of Chromecasts out in the market.
Chromecast threads: FAQ - READ THIS FIRST! / Rootable Serial Numbers | Root Mini-FAQ | FlashCast flashing Mini-FAQ
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