[libtorrent] Not possible to exchange trackers in master?

Discussion:

sledgehammer999

2017-01-08 22:52:36 UTC

I see that current master has removed the plugin that enables peers to
exchange trackers (lt_trackers).
Is this truly an obsolete feature? Is it a discouraged feature? Do other
popular clients drop this? Was it only limited to libtorrent-powered
clients?

In general what is the rationale of removing it?

Calum Lind

2017-01-08 23:12:24 UTC

Permalink

For reference it was marked deprecated in 1.1.1

commit 118d06b7808a9c4583f1c074a6b1d891b882615c
Author: Arvid Norberg <***@gmail.com>
Date: Sun Jul 24 23:39:56 2016 -0400

remove deprecated extensions lt_trackers and metadata_transfer (#941)

commit 6370d5bc812289b1de40052a785ce785d6856150
Author: Arvid Norberg <***@gmail.com>
Date: Sun Jul 24 23:37:03 2016 -0400

deprecate lt_trackers extension (#940)

deprecate lt_trackers extension

---------- Forwarded message ----------
From: Arvid Norberg <***@gmail.com>
Date: 20 September 2016 at 20:16
Subject: Re: [libtorrent] lt_trackers and metadata_transfer extensions
To: General discussion about libtorrent <
libtorrent-***@lists.sourceforge.net>

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 sledgehammer999
I see that current master has removed the plugin that enables peers to
exchange trackers (lt_trackers).
Is this truly an obsolete feature? Is it a discouraged feature? Do other
popular clients drop this? Was it only limited to libtorrent-powered
clients?
In general what is the rationale of removing it?
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Arvid Norberg

2017-01-09 00:50:08 UTC

Permalink

as far as I know, only libtorrent implemented this feature.
The main concern I had with it was the ability for anyone to inject their
tracker into peoples tracker lists and collect more information about them
than what otherwise would be possible, and especially easier.

I was also under the impression that it was not widely used, and that the
DHT also makes it obsolete to transition torrents to new trackers.

Post by Calum Lind
For reference it was marked deprecated in 1.1.1
commit 118d06b7808a9c4583f1c074a6b1d891b882615c
Date: Sun Jul 24 23:39:56 2016 -0400
remove deprecated extensions lt_trackers and metadata_transfer (#941)
commit 6370d5bc812289b1de40052a785ce785d6856150
Date: Sun Jul 24 23:37:03 2016 -0400
deprecate lt_trackers extension (#940)
deprecate lt_trackers extension
---------- Forwarded message ----------
Date: 20 September 2016 at 20:16
Subject: Re: [libtorrent] lt_trackers and metadata_transfer extensions
To: General discussion about libtorrent <
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.
org

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engaging tech sites, SlashDot.org! http://sdm.link/slashdot
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--
Arvid Norberg

sledgehammer999

2017-01-09 12:29:17 UTC

Permalink

Truth be told, I haven't investigated non-libtorrent clients. So I don't
know if they indeed used it.
In any case, this option was exposed in qbittorrent under the "Advanced"
section, so there is a chance that a lot of users didn't know about this
anyway.
I understand your concerns, and now I am toying with the idea of removing
the feature from qbt even when compiling against RC_1_0/RC_1_1.

Post by Arvid Norberg
as far as I know, only libtorrent implemented this feature.
The main concern I had with it was the ability for anyone to inject their
tracker into peoples tracker lists and collect more information about them
than what otherwise would be possible, and especially easier.
I was also under the impression that it was not widely used, and that the
DHT also makes it obsolete to transition torrents to new trackers.

very

Post by Calum Lind
similar code as ut_metadata. It has basically been obsolete since 2005.
lt_trackers is problematic because accepting and using an arbitrary

tracker

Post by Calum Lind
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

Post by Calum Lind
send less information in the announce if it comes from the extension.

This

Post by Calum Lind
only mitigates the problem though.
org

Post by sledgehammer999
I see that current master has removed the plugin that enables peers to
exchange trackers (lt_trackers).
Is this truly an obsolete feature? Is it a discouraged feature? Do

other

Post by Calum Lind

Post by sledgehammer999
popular clients drop this? Was it only limited to libtorrent-powered
clients?
In general what is the rationale of removing it?
------------------------------------------------------------
------------------
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engaging tech sites, SlashDot.org! http://sdm.link/slashdot
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--
Arvid Norberg
------------------------------------------------------------
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Michael Mckeown

2017-01-09 17:05:44 UTC

Permalink

I thought that it was a good feature till I asked why it was removed, in
practice you'll notice that when it's running you'll get tens even
hundreds of trackers added to torrents from sources like this:
http://www.torrenttrackerlist.com/torrent-tracker-list/ , more often
than not most don't work and some are suspicious trackers with just ip
addresses and port numbers.

Post by sledgehammer999
Truth be told, I haven't investigated non-libtorrent clients. So I don't
know if they indeed used it.
In any case, this option was exposed in qbittorrent under the "Advanced"
section, so there is a chance that a lot of users didn't know about this
anyway.
I understand your concerns, and now I am toying with the idea of removing
the feature from qbt even when compiling against RC_1_0/RC_1_1.

very

Post by Calum Lind
similar code as ut_metadata. It has basically been obsolete since 2005.
lt_trackers is problematic because accepting and using an arbitrary

tracker

and

Post by Calum Lind
send less information in the announce if it comes from the extension.

This

Post by Calum Lind
only mitigates the problem though.
org

Post by sledgehammer999
I see that current master has removed the plugin that enables peers to
exchange trackers (lt_trackers).
Is this truly an obsolete feature? Is it a discouraged feature? Do

other

Post by Calum Lind

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