Error: Host not found (authoritative)

[cokelid]

Deluge was working fine on Ubuntu, and then I started getting the following for all my torrents:

Tracker Status: ubuntu.com: Error: Host not found (authoritative)

I can nslookup and ping ubuntu.com on the machine so the DNS is working. (Obviously the "ubuntu.com" bit varies according to the tracker of the torrent.)

I've upgraded Ubuntu, but still the same issue. As I said, everything was working fine. I can only assume some package got upgraded?

Am running Ubuntu 12.04 (Precise Pangolin) and Deluge 1.3.5.

Googling suggests it could be a libtorrent error message, but I can't find out any more information or help.

Any ideas on how I could debug this? I've turned on logging, but I don't get any useful info in the log files...

Thanks!
Justin

[Cas]

It's not a Deluge issue so nothing would be logged: http://dev.deluge-torrent.org/ticket/1253

Also tracker.ubuntu.com is different from ubuntu.com

[cokelid]

Thanks for the reply Cas.

Indeed, the underlying host tracker is actually torrent.ubuntu.com, but I can resolve that (and ping it) from the command-line. The deluge error just mentions ubuntu.com (and similar for other torrents).

I appreciate that the error is probably generated by a (third-party) library used by Deluge, but hopefully it's still appropriate to discuss the problem here?

[Cas]

I don't know for sure but it's possible the error message may have stripped the 'torrent.' part off.

Have you checked your /etc/resolv.conf and /etc/hosts files?

It is fine discussing it here and if you find the solution it will help other users.

[cokelid]

Thanks again for the reply Cas.

So yes, I checked the resolv.conf (before I upgraded Ubuntu) and it pointed to my router as expected. After I upgraded to Ubuntu 12.04 resolv.conf points to localhost since 12.04 uses dnsmasq for DNS. Since the error occurred before dnsmasq was installed, it seems unlikely that's the culprit.

The /etc/hosts files looks fine too, just 2 entries: my localhost and my server (plus it now has some standard IPv6 entries).

I've looked at my libtorrent libraries (after reading this) but they look fine (i.e. no duplicates)?

Hmmm.

[cokelid]

Right - so I removed (purged) all the deluge packages, and any packages with "libtorrent" in the name. Then rebooted and then reinstalled deluge. Still the same problem.

Any more debugging ideas?

[Cas]

As I said it is not a Deluge or libtorrent issue so no that would not help. Have you asked on AskUbuntu or the Ubuntu forums/IRC?

[cokelid]

You're right Cas, it doesn't seem to be due to libtorrent since everything works fine with qbittorrent and rtorrent (which use libtorrent-rasterbar6 and libtorrent14 respectively).

Do you know what library is involved with the DNS lookup? If I can narrow it down to a particular library I can certainly jump on AskUbuntu or another forum, or do some testing myself.

I suppose it must be some library used by Deluge that isn't used by either of these two?

Thanks!
Justin

[Cas]

rtorrent is a completely different libtorrent but it is interesting that qbittorrent works ok. Could you be more precise about the libtorrent version used by qbittorrent as the only difference between qbittorent and Deluge is that we use the libtorrent python bindings but that should not affect how libtorrent communicates with trackers.

[cokelid]

Thanks once again Cas,

The installed versions I have are:
qbittorrent: 2.9.7-1
libtorrent-rasterbar6: 0.15.10-1

For deluged I'm using v 1.3.5 with
python-libtorrent: 0.15.10
libtorrent-rasterbar6: 0.15.10-1

If it's of interest:
libboost: 1.46.1