Packages: Transmission says port is closed even though it is open

Created on 16 Jan 2018 · 13Comments · Source: openwrt/packages

Maintainer: (not sure, mupliple people editing the makefile
Environment: Any recent LEDE (17.0.4). It does not matter which router is used.

Description: Even when one opens a port for transmission running on the router itself, Transmission still claims the port is closed: screenshot from 2018-01-16 12-25-18

This is a longstanding issue as can be seen here: https://forum.lede-project.org/t/transmission-always-reports-listening-port-closed/2615/27

No matter what configuration we put into /etc/config/firewall, the port stays closed. There are no problems with running transmission on one's PC as opposed to the router itself.

config rule
        option target 'ACCEPT'
        option src 'wan'
        option proto 'tcp udp'
        option dest_port '51422'
        option name 'Transmission-router1'

config redirect
        option target 'DNAT'
        option src 'wan'
        option dest 'lan'
        option proto 'tcp udp'
        option src_dport '51422'
        option dest_ip '192.168.2.1'
        option dest_port '51422'
        option name 'trans?'

config rule
        option enabled '1'
        option target 'ACCEPT'
        option src 'wan'
        option dest 'lan'
        option name 'Transmission-router2'
        option dest_port '51422'

Source

felagund

Most helpful comment

Good news. I found the issue. The libcurl in OpenWrt is built by default with zlib and verbose error strings disabled. After enabling both, The port checking feature correctly shows open. I'll figure out which but in the meantime, just ignore what transmission tells you.

neheb on 30 Jan 2018

🎉1 😄1 👍1

All 13 comments

Some other people having htis problem: https://forum.openwrt.org/viewtopic.php?id=62761
https://forum.openwrt.org/viewtopic.php?id=65856
https://forum.openwrt.org/viewtopic.php?id=70871
https://forum.openwrt.org/viewtopic.php?id=62250

It is reallt not a matter of misconfiguration.

felagund on 16 Jan 2018

And one more: https://forum.lede-project.org/t/port-is-open-but-transmission-says-its-closed/2580/2

felagund on 16 Jan 2018

It's probably an issue with the way transmission detects a closed port. It directs itself to visit a website and see the result. If anything fails, it reports a closed port. It should say unknown if the result from the website is not returned.

neheb on 22 Jan 2018

What is weird is that it works when I install transmission on my PC and Transmission does not report an open port even when I try to use some scanner website and it says the port in question is open.

felagund on 22 Jan 2018

Yeah. Like I said, transmission on OpenWrt cannot even get to the website due to some bug whereas it can on your computer. We'll see if I have time to investigate.

neheb on 22 Jan 2018

Debugged this a little bit...

transmission seems to require ca-bundle to work properly. Also CURL_CA_BUNDLE needs to be set. Once all that is done, it manages to connect to the test webpage with an HTTP code of 200. And fail to receive any data...

This might need adjustments to curl. Will investigate.

neheb on 24 Jan 2018

Thanks for investigation!

felagund on 24 Jan 2018

neheb on 30 Jan 2018

🎉1 😄1 👍1

@neheb If you really found the issue, you will please many people very much! I suppose the fix can be applied to LEDE, right?
Could you help us enable zlib and verbose error strings, while you search for an exact solution? If yes, please give newbie directions, me at least need a copy-paste guide to configure files and services. And please specify how your fix applies to LEDE if you can, because some configuration files are not the same as OpenWRT.
Sorry if I ask for too much and many thanks for any help!