Bittorrent tracker request

Question

Using a torrent file from

http://torrent.ubuntu.com:6969/

I am calculating its hash which matches with the hash on the page.

Then i make a request to the tracker. Like

http://torrent.ubuntu.com:6969/announce?info_hash=9a81333c1b16e4a83c10f3052c1590aadf5e2e20

But i get

d14:failure reason63:Requested download is not authorized for use with this tracker.e

According to the spec this should work?

Tracker Spec General Spec

Answer 1

You specified the info_hash in hex, rather than URL-encoding. The bytes of the SHA-1 hash should be encoded directly, like this:

http://torrent.ubuntu.com:6969/file?info_hash=%9A%813%3C%1B%16%E4%A8%3C%10%F3%05%2C%15%90%AA%DF%5E.%20

Also, for the announce URL, some additional parameters like peer_id are usually required.