Thoughtpile I write things here.

Install Syncthing on PocketBook

Installing Syncthing on a PocketBook is fairly easy, but it requires a bit more setup than on PCs. I’ve tested this with a PB632 (PocketBook Touch HD 3), but it should work on any PocketBook device.

Connect your e-reader via USB in “PC link” mode. Create the directory applications/syncthing in the storage device that shows up. Get the latest ARM 32 bit version of Syncthing from https://syncthing.net/downloads/ and extract the binary “syncthing” to the directory you just created. Now create the following files:

applications/syncthing.app
#!/bin/sh

SYNCTHING_DIR="/mnt/ext1/applications/syncthing"
${SYNCTHING_DIR}/syncthing -home="${SYNCTHING_DIR}"
applications/syncthing/config.xml
<configuration version="35">
    <gui enabled="true" tls="false" debugging="false">
        <address>0.0.0.0:8384</address>
    </gui>
    <options>
        <startBrowser>false</startBrowser>
    </options>
</configuration>
Note
PocketBooks don’t seem to have an address assigned to the loopback interface. If you try to listen on 127.0.0.1 Syncthing will exit with an error message.
Tip
If you want to see the output of Syncthing, download “pbterm.zip” from http://users.physik.fu-berlin.de/~jtt/PB/, install it and start syncthing.app from there.

Disconnect the e-reader, enable wireless LAN and start Syncthing. It should show up in “Apps” as “@syncthing”. Open a browser on your PC and connect to the IP of your PocketBook (see below if you don’t know it) on port 8384. Now configure Syncthing as normal. There is no window showing up if you start Syncthing, the screen appears to freeze. You can get back to your start screen with the home key. Syncthing will continue to run in the background. You can close Syncthing with the “Task Manager”.

Make sure that the Wi-Fi icon has black bars before starting Syncthing. When you don’t use the network for a short while, it goes into a sleep-mode and the Wi-Fi icon turns light-grey. Syncthing isn’t able to wake up the device, because (I assume) it would have to send a special command to the PocketBook-firmware and Syncthing doesn’t know it runs on a PocketBook. You have to turn the Wi-Fi off and on again, or do something that will wake it up like pressing the “Sync” button in the top menu, and then start Syncthing immediately. As long as an active connection is established, the Wi-Fi won’t go into sleep mode.

Important
PocketBooks use FAT as file system, which can’t store permissions. Make sure to check “Ignore Permissions” in the advanced tab for each shared folder or set ignorePerms="true" in config.xml. Otherwise the files will not be created. You will still get messages like “chmod […]: operation not permitted”. You can ignore them.
Caution
We configured Syncthing to accept connections to the configuration interface from everywhere without a password and we disabled encryption. Make sure to disable the GUI or set a password and enable TLS if you want to configure it in insecure networks.

How to find the IP address of your PocketBook

Connect the e-reader to your wireless LAN. If you’ve installed pbterm, open it and type ifconfig. The IP address comes after “inet addr:” in the output. Alternatively, open a terminal (also known as command prompt) on another computer on your network and type arp. In the “HWaddress” (“Physical Address” on Windows) column look for an address starting with 94:99:01 (the Windows command uses dashes instead of colons). The IP address is on the left.

Note
Different PocketBook models may use network chipsets from other vendors with different hardware addresses.