Add ability to disable PEX globally

[Pentaphon]

This is necessary for private tracker whitelisting. Can you add the ability for PEX to be disabled globally by clients such as libretorrent?

Requesting per advice on https://gitlab.com/proninyaroslav/libretorrent/-/issues/470

[tuxayo]

@Pentaphon are you sure that's what the private tracker needs? I though they mandated that for private torrents, the client would disable PEX for these torrents only.

A global option would rely on users toggling it. And it would hinder all their public torrents.

[Pentaphon]

@Pentaphon are you sure that's what the private tracker needs?

Yes, that ability to do that like qBittorrent does in their setting page. I believe simply adding this ability is enough to get libtorrent4j-based clients whitelisted because it would ensure that private torrents remain private. Public torrents would not be hindered as long as they use public announce URLs in addition to DHT.

[tuxayo]

Thanks for the update.

I believe simply adding this ability is enough to get libtorrent4j-based clients whitelisted

Is there a page with detailed rules for client whitelisting that you can link? To double check that this is necessary and also enough. Because that looks weird but maybe I'm confused and with all the details it will make perfect sense.

because it would ensure that private torrents remain private

It would ensure nothing since it depends on users using that setting. I haven't seen many private trackers, but still I don't recall them asking users to manually turn off PEX globaly.

Public torrents would not be hindered as long as they use public announce URLs in addition to DHT.

PEX is useful for public torrents because trackers after years eventually die and DHT might not work well due to firewall issues that a lot of users don't know how to fix. Or don't have access to. (possibly including nationwide firewalls).So PEX is another thing helping as much as possible peers knowing eachother's existence. And then even with firewall issues for a peer, if the other can accept incoming connection, the firewalled one can still connect to the other. (If I understand correctly)

And otherwise, we could remove PEX completely. Much simpler. A bit of network traffic and CPU load spared as a bonus.

Still on DHT, I have to disable it because due to some horrible bug on my ISP router, DNS queries randomnly fail when DHT is on (for everyone in the network!). Even with a custom DNS. I've seen it from 3 places with the same ISP which is used by 20% of france 😱. And on the 3 places, it's not me who can decide the ISP. And on the 3 places, it's the only ISP with FTTLA. The others are still on ADSL… (to be fair, I'm unlucky on that last point, and the 20% of france include proper fiber and ADSL with a different router family likely without that bug)
It's just an example where PEX really saves the day.

like qBittorrent does in their setting page

It doesn't matter for qBittorrent, I left the default settings with PEX globaly on, and my private torrents still show PEX disabled for them because they are private. And that's what matters for private torrents. While PEX still shows getting peers on my public torrents.

But maybe with details from some tracker rules, all of this could be understood differently.

[Pentaphon]

Is there a page with detailed rules for client whitelisting that you can link?

No because these trackers are private. In order for them to whitelist libtorrent4j-based clients like libretorrent, libtorrent4j needs to reach private torrent feature parity with desktop clients like Transmission. If any staff reading this would like to speak up here, please do.

Private tracker staff have pointed to these 2 issues missing from libretorrent in order for it be whitelisted and the author of libretorrent suggested I report 470 upstream.

https://gitlab.com/proninyaroslav/libretorrent/-/issues/470
https://gitlab.com/proninyaroslav/libretorrent/-/issues/471

PEX is useful for public torrents because trackers after years eventually die

I'm fully aware of this, but this is what private trackers require for libretorrent to be whitelisted. Since all the major clients like Transmission and qBittorrent allow PEX to be disabled globally, I would think it would be ok to do the same on mobile clients as well.

[tuxayo]

Thanks for reaching out to the tracker staff.

No because these trackers are private

Fair enough. Is copypasting the text here ok then? We might be in a case of: https://en.m.wikipedia.org/wiki/Telephone_game which causes confusion.

libtorrent4j needs to reach private torrent feature parity with desktop clients like Transmission.

Which isn't about global settings but about disabling stuff on individual private torrents. (BEP 27)

Private tracker staff have pointed to these 2 issues missing from libretorrent in order for it be whitelisted

In these two tickets, there is a need to clarify if the trackers need "A global option for users to disable PEX. And that it's not about automated disablement of PEX on individual private torrents"

Because if it's actually about "automated disablement of PEX on individual private torrent". Then there is no need to change anything because libtorrent4j is compliant with BEP 27, see readme: https://github.com/aldenml/libtorrent4j?tab=readme-ov-file#libtorrent4j

So we are a snake biting our own tail when looking at the two tickets on libretorrent ^_^ Because there are the same questions as here.

and the author of libretorrent suggested I report 470 upstream.

It seems we are all confused in this story. Because in another ticket, the author of LibreTorrent confirmed PEX is not active for private torrents. Someone though it was active and the author said the UI was wrong:
https://gitlab.com/proninyaroslav/libretorrent/-/issues/235

Since all the major clients like Transmission and qBittorrent allow PEX to be disabled globally, I would think it would be ok to do the same on mobile clients as well.

This needs to be sure to be about "qBittorrent allow PEX to be disabled globally".

Because the actual standard for private torrents doesn't mention disabling things globally: https://www.bittorrent.org/beps/bep_0027.html

BitTorrent has currently four ways that a peer can learn of other peers in a swarm:

When a BitTorrent client obtains a metainfo file containing the "private=1" key-value pair, it MUST ONLY announce itself to the private tracker, and MUST ONLY initiate connections to peers returned from the private tracker.
[…]
Trackers [1],
Distribute Hash Table (DHT) [2],
Peer EXchange (PEX) [3],
Local Service Discovery (LSD) [5].
Announcing or exchanging peer information via any of these mechanisms other than the private tracker subverts the tracker's access control.

All this is automated on private torrents only. Not a global manual setting.

Thanks again for your time looking into that problem.