Discussion:
[libtorrent] lt_trackers and metadata_transfer extensions
Michael Mckeown
2016-09-20 13:13:13 UTC
Permalink
How come these extensions were removed? The fetching of trackers from
other peers worked quite well and if your into trackers it seemed a
natural thing to do.
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Arvid Norberg
2016-09-20 19:16:07 UTC
Permalink
transfer_metadata is an extension that predates uTorrent's metadata
transfer extension (ut_metadata). It's more complex and less relevant
(since only libtorrent supports it). It's also redundant, and contains very
similar code as ut_metadata. It has basically been obsolete since 2005.

lt_trackers is problematic because accepting and using an arbitrary tracker
from an untrusted source lets it:

1. use you in launching DDoS attacks against web sites
2. make you reveal more information about yourself than you may want

To mitigate (2), there's also logic to remember the source of a tracker and
send less information in the announce if it comes from the extension. This
only mitigates the problem though.
Post by Michael Mckeown
How come these extensions were removed? The fetching of trackers from
other peers worked quite well and if your into trackers it seemed a
natural thing to do.
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Arvid Norberg
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Michael Mckeown
2016-09-21 11:25:55 UTC
Permalink
Got it, thanks.
Post by Arvid Norberg
transfer_metadata is an extension that predates uTorrent's metadata
transfer extension (ut_metadata). It's more complex and less relevant
(since only libtorrent supports it). It's also redundant, and contains very
similar code as ut_metadata. It has basically been obsolete since 2005.
lt_trackers is problematic because accepting and using an arbitrary tracker
1. use you in launching DDoS attacks against web sites
2. make you reveal more information about yourself than you may want
To mitigate (2), there's also logic to remember the source of a tracker and
send less information in the announce if it comes from the extension. This
only mitigates the problem though.
Post by Michael Mckeown
How come these extensions were removed? The fetching of trackers from
other peers worked quite well and if your into trackers it seemed a
natural thing to do.
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------------------
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https://lists.sourceforge.net/lists/listinfo/libtorrent-discuss
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