Please note: That info is for tracker admins, if you are an Azureus user and want to disable the Distributed tracker for a specific torrent rightclick on the torrent, go to Advanced > Peer sources and uncheck decentralized tracking
 Secure Azureus Torrents
Tracker sites wanting to ensure that Azureus only obtains peers directly from the tracker itself (besides incoming connections) should embed the key "private" with the value "1" inside the "info" dict of the .torrent file:
Azureus clients, upon seeing this flag set, will disable any sort of external peer exchange for that torrent. That means Azureus behaves like a classic BT client without PEX or DHT, meaning only peers given out by the tracker will be used for outgoing connections, even if that tracker goes down, as it is normally today.
This new field will be ignored by other BT clients, so it does not break compatibility as long as they've properly implemented the BT spec. Also, this new field WILL change the torrent's infohash, which means that torrents made without the secure flag aren't compatible with torrents made with it. If you update all the torrents on your web site, you will have to ask users to re-download the torrent files in order to let them connect to your tracker.
The Azureus Team recommends only using this flag for new torrents, as it'll provide a smooth transition for your users.