A fully VPN’ed family member got hit with an automated copyright strike and when looking into how it happened I found out that using the default qBittorrent config with a killswitch-enabled ProtonVPN meant that the home IP address was being leaked. I verified it through a few tools, including ipleak(dot)net’s fake magnet link feature which showed both the VPN and home IPs when connected. I’m at best a tinkerer so I’m not sure if this is a Proton-exclusive problem at all, or if the killswitch useage is even relevant, but that’s what they were using and figured this all might be worth mentioning since it was certainly a shock to us and not something we’ve seen brought up before.
The solution was to change which network interface qBittorrent was set to use via “Tools > Preferences > Advanced > Network interface”. Which one to pick will depend on the protocol you’re using in Proton’s client, but unless you’re confident in what you’re doing I’d recommend testing each with the ipleak(dot)net (or similar) torrent tool until you’re only seeing the VPN IP show up.
Hope this is useful! (and not common knowledge that we were just wildly ignorant of)
I think proton has two levels of ‘killswitch’ on it’s VPN. The regular one is more of a ‘killswitch but only when you have the app open’ while the extra options are supposed to make it an actual kill switch. Whether or not this second level is completely effective I can’t say.
Binding your client to the vpn interface is definitely the way to go. This safety measure is widely known, but I feel that it is much less well known than it should be.
For the record the “Advanced” killswitch mode is what was used, so their assumption was that nothing would be able to leak and would, in worst case scenarios, just not connect at all. Which was definitely not the case.