Jump to content
To block spammers, this forum has suspended new user registration ×
Comet Forums
To block spammers, this forum has suspended new user registration

DHT Not connected? <---READ


Recommended Posts

BitComet's DHT system is a nice addition, but it is NOT necessary for downloading and enjoying torrents. If your client shows that DHT is not connected, it is not a huge problem, or even a minor one, and you can do perfectly well without it.

DHT is a system that is overlaid on top of Bittorrent, and its function is to find more peers than the tracker supplies you. Most of the time, you don't need any more peers. Very, very rarely is DHT any help.

The torrent creator, whoever that may be, can choose to disable DHT for the torrent. If that is done, then DHT won't work at all. Many private torrent sites require their uploaders to disable DHT, so that it cannot be used anyway, even if you have it otherwise working.

DHT uses a protocol called UDP. Bittorrent uses a counterpart protocol called TCP. Most network applications like your web browser and your email client are TCP-based. It is a two-way protocol, where UDP is one-way, which is why it's not used very much.

Your firewall blocks outside attempts to communicate, because many of those attempts are malicious. When you tell the firewall to allow an application through the firewall, it will do so. Most of the time, for most firewalls, the default setting for this is to allow TCP only -- because that's what the majority of applications use. They don't care about UDP, so that can remain blocked.

For DHT to work, your firewall must allow both kinds of traffic, UDP and TCP, on the BitComet listen port. If you change or add your firewall rule for Bitcomet to allow UDP too, then DHT usually starts working.

Do NOT attempt to solve things by disabling your firewall. Connecting to the internet without a firewall is both dangerous and stupid.

All you will get, if it does start working, is maybe a few extra peers. DHT by itself will not speed up your download or affect your transfer in any way. Most of the time, you get more peers from the tracker than you can possibly connect to anyway, so having some extras doesn't really help.

As you transfer, your bittorrent client picks the best and fastest peers to download from. It does not care how they were found. So even if you have DHT working, and it does find some peers, they may not even be used.

Read more here http://en.wikipedia.org/wiki/Distributed_hash_table

Link to comment
Share on other sites

Actually, I experienced firsthand just how helpful DHT was last night. I kept tracking the trackers and peers and I was logged on to DHT. I had in the 1000s available and each file downloading was using 7-50 of those when the tracker site kept returning 0 or error connecting.

I had to reboot today and when I got bitcomet back up, same files downloading as before, DHT was not connected and hasn't since. Now I don't get the last 2 mg of my file I waited all day for as the tracker errored out and DHT isn't connected.

From reading this article I assume I have no control on connecting DHT myself? It either connects because no one has blocked it from any of the tracker sites or it connects itself if no tracker sites block it?

Wish I knew. :angry:

  • Like 1
Link to comment
Share on other sites

The tracker has nothing whatever to say in the matter. DHT completely bypasses the tracker.

The DHT network is entirely peer-to-peer, what is called a "distributed database", in which each node has a portion of the whole. When you join the DHT network, your client also becomes a host for part of the data, as well as a client making inquiries of it.

This is a pretty huge idea, because it lets you have a really big database without needing a really big server, or much of any server at all. This application of it is maybe a little banal, but it does work well.

It is the torrent that matters. The creator of the torrent, at the time it's created, decides whether to make a torrent that supports DHT (and a similar system called PEX), or not. Nobody can subsequently override that choice either way.

Some of the tracker sites require that whoever uploads torrents to their site use only "private" torrents, those with DHT and PEX disabled. If somebody violates that rule, and they find out, I imagine they'll delete the torrent and warn or ban the offender. But there's nothing they can do to disable it short of deleting the torrent.

DHT definitely has its uses. It was created so that somebody could distribute a torrent from, say, a blog, without needing to set up a tracker. It can and does work for that, but so far only Azureus has actually followed through and done it. BC claims the ability, but no one I know including myself, has ever actually gotten it to work.

In some future dystopia, where trackers are somehow banned, bittorrent will continue without them via DHT.

Link to comment
Share on other sites


Shazil, your comment for Kluelos is very kind, and welcomed, but I did edit a few dozen links of "OOOOO"s out, as it makes the topic an easier read.


NOTE: to other members reading this post. Any comments about this guide are welcome here, as are comments thanking the writer, or in the case of Shazil, showing affection for. This is all very acceptable, HOWEVER, this is not the approiate topic to post problems you are having, and this topic is not monitored regularly for support questions.

So, post your thank you...

post your comments related to this guide, NOT your problem or support issue.

Link to comment
Share on other sites

  • 2 weeks later...

So what's the difference between Preferences-->Connection-->"Enable DHT network" and each torrent's Properties-->Advanced-->"Enable Public DHT Network"?

You can turn it on or off for all torrents, or for one particular torrent as desired.

Link to comment
Share on other sites

  • 2 weeks later...


I have my DHT disconnected, I read your explanation, I went to the windows firewall, I checked i have BitComet 13791, 16353, 19016 and 9071 all allowed TPC and UPD. Can you help me... what do those number means?

Another question is... why do i have this in my torrentspy? "You are currently managing 0 torrents." If I already downloaded many things? What do I have to do?

Thanks a lot!!!

Link to comment
Share on other sites

This topic is now closed to further replies.
  • Create New...