transmission-daemon can't connect to one specific tracker

[jgabor]

This problem is really odd and just appeared a couple of days ago.

My server at home running Ubuntu 12.10 x64 with transmission-daemon 2.77 as it's BitTorrent-client just stopped being able to connect to a specific tracker. The problem started already with the previous version of transmission-daemon, I upgraded to see if it would help. Other trackers works just fine on the server and this tracker works fine from other computers. So everything works as it should except when trying to connect to this specific from the server, which I find very odd since the server can connect to every other tracker I've tried. I can also curl the announce URL without trouble from the same server. So I've ruled out any network or port forwarding issues...

I've run transmission-daemon with " transmission-daemon -f --log-debug" to see if it prints any weird error messages, but so far it hasn't said anything at all... I also can't find any log files in /var/log, so any pointers where these are saved would be very helpful.

I'm stuck in the troubleshooting. I can't find any problems at all. Anyone have any suggestions on where to look further?

[rb07]

can't find any log files in /var/log

Transmission logs to the regular system log: messages.

transmission-daemon -f --log-debug" ... hasn't said anything at all

Really? Nothing at all probably means its not even running, never started... uh wait! what user is doing that run? It does change everything if you start the daemon as a regular user, or root, or the user set by the start-up script.

That has to be the weirdest statement of the year on this forum

But I've never tried with --log-debug, perhaps there's something wrong with that parameter; try without it.

[jgabor]

Really? Nothing at all probably means its not even running, never started... uh wait! what user is doing that run? It does change everything if you start the daemon as a regular user, or root, or the user set by the start-up script.

My bad. I thought it would print out to the standard input and the log file. Here's the output in the log:

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[19:28:48.792] Transmission 2.77 (14031) started (session.c:722)
[19:28:48.792] RPC Server Adding address to whitelist: 127.0.0.* (rpc-server.c:803)
[19:28:48.792] RPC Server Adding address to whitelist: 192.168.*.* (rpc-server.c:803)
[19:28:48.792] RPC Server Serving RPC and Web requests on port 127.0.0.1:9091/transmission/ (rpc-server.c:997)
[19:28:48.792] RPC Server Password required (rpc-server.c:1004)
[19:28:48.792] Couldn't bind port 50123 on 0.0.0.0: Address already in use (Is another copy of Transmission already running?) (net.c:369)
[19:28:48.792] Couldn't bind port 50123 on ::: Address already in use (Is another copy of Transmission already running?) (net.c:369)
[19:28:48.792] UDP Couldn't bind IPv4 socket (tr-udp.c:262)
[19:28:48.792] DHT Reusing old id (tr-dht.c:305)
[19:28:48.792] Using settings from "/home/username/.config/transmission-daemon" (daemon.c:517)
[19:28:48.792] Saved "/home/username/.config/transmission-daemon/settings.json" (bencode.c:1738)
[19:28:48.792] transmission-daemon requiring authentication (daemon.c:537)
[19:28:48.792] Watching "/home/username/Downloads" for new .torrent files (daemon.c:555)
[19:28:48.792] Using inotify to watch directory "/home/username/Downloads" (watch.c:73)
[19:28:48.792] Loaded 7 torrents (session.c:1943)
[19:28:48.792] Port Forwarding (NAT-PMP) initnatpmp succeeded (0) (natpmp.c:72)
[19:28:48.792] Port Forwarding (NAT-PMP) sendpublicaddressrequest succeeded (2) (natpmp.c:72)
[19:28:52.795] Port Forwarding (UPnP) Found Internet Gateway Device "http://192.168.0.1:80/WANIPConnection" (upnp.c:200)
[19:28:52.795] Port Forwarding (UPnP) Local Address is "192.168.0.19" (upnp.c:202)
[19:28:52.795] Port Forwarding (UPnP) Port forwarding through "http://192.168.0.1:80/WANIPConnection", service "urn:schemas-upnp-org:service:WANIPConnection:1". (local address: 192.168.0.19:50123) (upnp.c:277)
[19:28:52.795] Port Forwarding (UPnP) Port forwarding successful! (upnp.c:280)
[19:28:52.795] Port Forwarding State changed from "Not forwarded" to "Forwarded" (port-forwarding.c:93)
[11:01:51.915] Torrent.Name.Goes.Here Announcing to tracker (announcer.c:1532)
[11:02:51.943] Torrent.Name.Goes.Here Could not connect to tracker (announcer.c:994)
[11:02:51.943] Torrent.Name.Goes.Here Retrying announce in 7237 seconds. (announcer.c:1003)

So it looks like it can't bind port 50123 although the UPnP and NAT-PMP port forwarding does succeed. The odd thing is, checking open ports with "lsof -i 4" it looks like it has managed to bind the ports:

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~$ lsof -i 4 | grep 50123
transmiss 13785 username   11u  IPv4  919725      0t0  TCP *:50123 (LISTEN)
transmiss 13785 username   13u  IPv4  919728      0t0  UDP *:50123

And deluged has no trouble binding the ports if transmission-daemon is stopped. The process list also shows only one running instance of transmission-daemon:

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~$ ps aux | grep transmission
1000     13785  0.3  0.3 311616 32704 pts/1    Sl+  Apr28   3:03 transmission-daemon -f --log-debug -e transmission-daemon.log
1000     27841  0.0  0.0   9400   884 pts/0    S+   11:20   0:00 grep transmission

Sorry for the lengthy post, I just wanted to get you guys as much information as possible. I really would like to figure this out.

[jgabor]

Just restarted transmission-daemon and this time it managed to bind the port:

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[13:00:39.738] Bound socket 11 to port 50123 on 0.0.0.0 (net.c:377)
[13:00:39.738] Bound socket 12 to port 50123 on :: (net.c:377)
[13:00:39.738] UDP Failed to set send buffer: requested 1048576, got 262142 (tr-udp.c:88)
[13:00:39.738] UDP Please add the line "net.core.wmem_max = 1048576" to /etc/sysctl.conf (tr-udp.c:93)

I added the suggested net.core setting to sysctl.conf and restarted transmission-daemon once again. The suggestion disappeared but unfortunately the problem with connecting to the tracker did not…

I disabled PEX, LPD and DHT to see if it made any difference, but nope. That didn't help either.

Any and all suggestions are very welcome at this point.

[jgabor]

I just upgraded the server to Ubuntu 13.04 and presto, transmission-daemon could magically connect with any issues whatsoever!

Sorry to disappoint others with the same issue and hoping for a solution to this and can't for some reason upgrade their servers…