Problem with Transmission in LAN

Ask for help and report issues not specific to either the Mac OS X or GTK+ versions of Transmission
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Hawkoon
Posts: 3
Joined: Thu Aug 05, 2010 12:40 pm

Problem with Transmission in LAN

Post by Hawkoon »

Hello All,

hope I can find some help here after googling for days without finding relevant answers.

So far I only used Transmission to download stuff from the internet and it always worked great. But now I want to use the bittorrent protocol to share files with friends (since it is more than one friend and torrents are robust against interruption I thought this might be a better approach than using FTP). Before sending out my torrent file I thought I do a test in my LAN to check if everything is working.

So I have two computers in my LAN. On PC1 I created a torrent file using a public tracker, and added it to Transmission (v1.75). I then copy the torrent file to PC2 and add it to Transmission (v1.34). Even after hours of waiting PC2 has still not received any data.

Status on PC1 (seeder) is: Seeding to 0 of 0 connected peers - Idle, and: Tracker responded: Success
Status on PC2 is: Downloading from 0 of 0 connected peers - Data not fully available, and: Tracker responded: OK (200)

If both ends are talking to the tracker, why can't they talk to each other? I have the feeling that I might have a port issue (both Transmissions tell me that the port is closed), but then both PCs can download data when I add internet torrent files. Why is my own torrent file not working, what am I missing?

Any help will be much appreciated, even if it is pointing out fundamental errors in my thinking :)
rb07
Posts: 1400
Joined: Sun Aug 24, 2008 3:14 am

Re: Problem with Transmission in LAN

Post by rb07 »

Hawkoon wrote:If both ends are talking to the tracker, why can't they talk to each other? I have the feeling that I might have a port issue (both Transmissions tell me that the port is closed), but then both PCs can download data when I add internet torrent files. Why is my own torrent file not working, what am I missing?
If the "port is closed" then transmission can't upload.

Being able to download doesn't mean you are able to upload Your server has to upload, and all clients will also have to upload if you want to really use the distributed file sharing part.

How to solve a port closed? You have to map your public IP and port to your server, that is done at the router/modem/gateway, or using the UPnP/NAT-PMP functionality if the modem/etc. does have that option.
jch
Posts: 175
Joined: Wed May 13, 2009 12:08 am

Re: Problem with Transmission in LAN

Post by jch »

rb07 wrote:If the "port is closed" then transmission can't upload.
Nonsense.

If the port is closed, Transmission cannot accept incoming connections, but it can still make outgoing connections. Both incoming and outgoing connections can be used both for upload and download.

Obviously, if two peers can only make outgoing connections, there's no way for them to connect to each other.

--jch
rb07
Posts: 1400
Joined: Sun Aug 24, 2008 3:14 am

Re: Problem with Transmission in LAN

Post by rb07 »

jch wrote:Nonsense.
Did you read the context?

That was not a general "can't upload", it was a very specific, for a transmission-daemon as first and only seeder, response.
Hawkoon
Posts: 3
Joined: Thu Aug 05, 2010 12:40 pm

Re: Problem with Transmission in LAN

Post by Hawkoon »

Thanks for your pointers so far. The message is clear, I have to figure out those ports.

Just to clarify, I trying to do a 1-to-1 transfer between two PCs on the same LAN to test my torrent file.

The router/modem I am connected to is at my neighbours, so I only have my VNC port (5500) available for experimenting for the time being. I shut down the VNC server and configured my seeding PC1 to use that port (and Transmission tells me it is open). PC2 has no port forwarded (until I get hold of my neighbour).

The data transfer should be working in at least one direction now - if I understand your posts that is - since one of the PCs has an open port available which allows it to make outgoing and accept incomming connections. However, I still don't get any data transfer. If I make PC2 the seeder (with the closed port) it is the same: no data transfer. Maybe the problem is caused by the fact that both PCs are on the same LAN? Anyway, I'll try to get an open port for PC2 as well and see what happens then.
x190
Posts: 5094
Joined: Sun Nov 30, 2008 4:59 am

Re: Problem with Transmission in LAN

Post by x190 »

New versions have Local Peer Discovery capability. Would that help?

https://trac.transmissionbt.com/wiki/Ed ... Files#Misc

http://www.transmissionbt.com/download.php
Hawkoon
Posts: 3
Joined: Thu Aug 05, 2010 12:40 pm

Re: Problem with Transmission in LAN

Post by Hawkoon »

I didn't know about the LPD option, interesting. Although, in my case I prefer to run with a "standard" config since my aim is to test a torrent file, that is to simulate a friend connecting and downloading from my seeding PC. So even both my PCs are in the same LAN, I rather not have them connect directly for the bittorrent transfer.

Anyway, in the meantime I did some more testing. With the bittorrent port open for one PC and closed for the other, I managed to get my data transferred from the one with the closed port to the one with the port open. It doesn't reproduce very well though; sometimes the data transfer starts as soon as both Transmissions are online, some other times it takes ages. Maybe that is a bittorrent feature though, I don't know. I might experiment a bit more, but fo the time being I think I will stick to FTP, it behaves in a more predictable manner.

Thanks everyone for your input - I certainly learnt a lot here :)
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