Transmission on two servers; unable to communicate with each other

[fogster]

I'm having a weird issue I can't quite figure out. I don't think it's a Transmission bug, but I'm hoping someone can help me figure out what's wrong with my setup.

I'm running Transmission (specifically, transmission-daemon on Linux) running on two servers in different data centers. (In fact, on different continents.) One is a seedbox, and the other is running on my personal server. In both cases, I am able to join swarms, download content, and upload content just fine. Most (possibly all) peer connections show an "I" for Incoming, so the problem is not that the port is not open.

But my two Transmission instances refuse to talk to each other. They show up in each others' peer lists, and will collect different parts of the file (as they should). But they refuse to share with each other. One side shows 'd', for 'We would download from this peer if they would let us'. The other side shows a 'u' -- 'We would upload to this peer if they asked'.

Questions about this pop up in the forum and on Google; the answer is generally pretty simple -- there are a limited number of slots, and they might be filled up on the remote side. Normal stuff. But in this case I'm controlling both sides, and know that each instances of Transmission has fewer than 10 active peers total, and is configured for 100 per torrent and 400 globally. Neither should be near the limit, unless I misunderstand how the limit works.

I'm stumped. Neither side is using a blacklist. And from either server, I can use netcat to open a connection to the other server's port successfully, so it doesn't seem like a connectivity/firewall issue. And I can talk to other peers. But my servers steadfastly refuse to share with each other. What should I check to debug this further?

[cfpp2p]

Tools I use to debug situations like yours:

There is no out of the box way to force client connection.

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Create your own unique torrent and try that.

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Use blocklists.

https://trac.transmissionbt.com/wiki/Mo ... Blocklists
examples:

block-exceptions.txt
# substitute X as per rules
block ALL x:0.0.0.0-7X.109.154.211
block ALL x:7X.109.154.213-192.168.1.76
block ALL x:192.168.1.78-255.255.255.255
# allows only the two peers 7X.109.154.212 and 192.168.1.77

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Use whitelist and blocklist
https://sourceforge.net/p/transmissiond ... /2b773cb5/
https://github.com/cfpp2p/transmission/ ... 54060ca67b
examples

block-all.txt
block ALL x:0.0.0.0-255.255.255.255

allow-whitelist.txt
# substitute X as per rules
allow x:6X.222.110.8-6X.222.110.8
allow x:192.168.1.77-192.168.1.77
# allows only the two peers 6X.222.110.8 and 192.168.1.77

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Manual "add peer" to individual torrents
https://sourceforge.net/p/transmissiond ... /2c267046/
https://github.com/cfpp2p/transmission/ ... 45ecb0873f