Fedora media writer checksum iso

xerxes1511 · September 1, 2021, 6:04pm

hello everyone

i read the last article from fedora magazine and there was mention of fedora media writer.
I want to try fedora media writer only I can’t find anything about whether the writer checks the checksum.

huben · September 1, 2021, 7:09pm

Not sure if it does, maybe not.
However, you can check the checksum yourself.

How is described here:

You also can write an iso to usb using the “dd” command.

(Assuming you try to write the “Fedora-Workstation-Live-x86_64-34-1.2.iso”.)

First find your device, e.g with “lsblk”.
If you have problems finding it, see this link:
https://docs.fedoraproject.org/en-US/Fedora/20/html/Installation_Guide/Making_USB_Media-UNIX_Linux-other-dd.html

Then write it to USB, we now asume it would be /dev/sdx
sudo dd if=Fedora-Workstation-Live-x86_64-34-1.2.iso of=/dev/sdx bs=512k
→ note, your Data on USB will now get lost.
This probably goes a bit fast, that’s why you may need to use sync to actually write it:
sudo sync
wait a bit
eject /dev/sdx
And if you now remove and re-attach your usb stick, you should have your Fedora Install Live Media.
Verify it with “lsblk”

sdx            8:96   1   3,6G  0 disk 
├─sdx1         8:97   1   1,9G  0 part /run/media/ben/Fedora-WS-Live-34-1-2
├─sdx2         8:98   1   9,9M  0 part 
└─sdx3         8:99   1  20,9M  0 part

xerxes1511 · September 2, 2021, 3:04am

thank you

I always use GNOME disk works great. I was only interested in how the media writer does it because according to the fedora guide he is the official usb stick creation.

huben · September 2, 2021, 5:41am

I found some info at the project page:

github.com

FedoraQt/MediaWriter/blob/main/CRYPTOGRAPHY.md

# Cryptographic features of Fedora Media Writer

There are two separate checksum validation processes integrated in the Fedora Media Writer.

## SHA256 hash

All Fedora images (except Atomic) have a SHA256 hash assigned when created. This hash is included in the release metadata that's included in Fedora Media Writer and also in the releases.json file that's provided as a part of Fedora Websites and served over HTTPS.

Fedora Media Writer then computes SHA256 hash of the ISO data being downloaded to check if the image is counterfeit or not.

## Integrated MD5 ISO checksum

All Fedora ISO images have an integrated MD5 checksum for integrity purposes.

Fedora Media Writer verifies this checksum right after the image is downloaded and also after the image has been written to a flash drive to verify if it has been written correctly.

So yes, at least for Fedora Images it does perform a checksum verification.

Looks like they use “dd” for the media creation under Linux.

github.com

FedoraQt/MediaWriter/blob/main/README.md

# Fedora Media Writer

Fedora Media Writer is a tool that helps users put Fedora images on their portable drives such as flash disks.

It is able to automatically download the required image for them and write them in a `dd`-like fashion, using either `dd` itself or some other way to access the drive directly.

This overwrites the drive's partition layout though so it also provides a way to restore a single-partition layout with a FAT32 partition.

![Fedora Media Writer running](/dist/screenshots/linux_main.png)

## Troubleshooting

If you experience any problem with the application, like crashes or errors when writing to your drives, please open an issue here on Github.

Please don't forget to attach the FedoraMediaWriter.log file that will appear in your Documents folder ($HOME/Documents on Linux and Mac, C:\Users\<user>\Documents). It contains some non-sensitive information about your system and the log of all events happening during the runtime.

## Building

You can build FMW using the default Qt `cmake` build system. The gist for all three platforms is written below. For a more thorough look into how the releases are composed, you can read our [GitHub Actions configuration](https://github.com/FedoraQt/MediaWriter/blob/master/.github/workflows/ccpp.yml).

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straycat · September 2, 2021, 12:50pm

I’ve used the fedora media writer for quite awhile and as Ben posted it checks the iso.Unless it’s changed it does that on all fedora and red hat based iso’s.

xerxes1511 · September 2, 2021, 7:59pm

thank you

I tried the writer and it works great

augenauf · September 3, 2021, 9:04am

just fyi, updated documentation can be found here: https://docs.fedoraproject.org/en-US/quick-docs/creating-and-using-a-live-installation-image/#_using_a_direct_write_method

augenauf · September 3, 2021, 11:20am

Do you think the information is important enough to add it to Fedora Documentation?

Preparing for Installation :: Fedora Docs and in Quick-Docs: Creating and using a live installation image :: Fedora Docs

@ankursinha

ankursinha · September 3, 2021, 1:50pm

Yes, certainly. Would anyone like to open pull requests to the docs to add this info?