By "etc." you're probably thinking of zsync. (There are also .metalink files but those are for automatic web download mirror selection.)

Why isn't ed2k supported as a primary distribution method for Ubuntu, alongside the other methods? This is probably because the eDonkey network:

1. is considerably less popular than bittorrent. The more people use a peer-to-peer distribution method, the more effective it tends to be in assuring high speed and reliability.


2. does not offer the unique, highly specialized advantages that motivate some developers and users to use jigdo to construct server ISO images (jigdo does not support the usual desktop ISOs).


3. does not offer the HTTP compatibility/integration of zsync or its ability to facilitate selective downloading of missing pieces of an ISO, even for desktop ISO images.

I believe the two most popular ways Ubuntu is downloaded are:

• traditional download (HTTP and, to a lesser extent, FTP)


• bittorrent

Downloading with a web browser (or ftp client) or with bittorrent are far more popular, among computer users at large, than any of the other distribution methods discussed above. It's no surprise that if only one standard peer-to-peer system is to be supported, it is bittorrent.

If you believe ed2k ought to be supported and are able and willing to present a compact, well-reasoned argument for this--to succeed, I think you'd most likely have to look up usage statistics to informally demonstrate that there users of EDonkey network clients who might be interested in downloading Ubuntu in that way--then you might consider filing a feature request against the ubuntu-website project on Launchpad.

On the other hand, if your goal is just to personally download Ubuntu with aMule, you might be able to do that, if you can find users on the EDonkey network (or other networks supported by the aMule client) who are sharing the ISO image you want. Especially if you download Ubuntu in this way, I highly recommend you verify its hash to ensure authenticity and integrity. If security is a concern, an MD5SUM is far better than nothing but a SHA-1 or SHA-2 hash is preferable. (All are provided for official Ubuntu ISOs.)