Network interface bind not respected for tracker announces

[Tadsz]

qBittorrent: 3.3.7
Qt: 5.7.0
libtorrent: 1.0.10.0
boost: 1.61.0
OS version: W10 Pro

I did not see a fix for this problem in the changelog for upcoming versions

When bound to a specific network interface (VPN), some trackers are still announced over the default network interface causing another IP to bleed to the tracker. Not all trackers continue to work but a lot keep working (did not find a difference for http/https)

Steps to reproduce:

• Bind qBittorrent to a disconnected interface (VPN, but disconnected) and restart qBittorrent for changes to take effect. This should mean no network traffic to trackers and therefore announces must fail.

• Add a list of torrents with various trackers as it's only a fraction of trackers that announce outside of the bound interface.

• Check which trackers report a working announcement and check with those trackers to see what IP is reported.

When a firewall rule is made to block qBittorrent and that rule applied only to the not-bound interface while the bound interface (VPN) is disconnected, then all trackers fail. If the bound interface is connected then all trackers succeed. The firewall log still shows a lot of connections through the not-bound interface.

[ghost]

I can confirm also.

Looking at Wireshark, qBittorrent also attempts to retrieve the favicons for the trackers with a HTTP GET request outside of the VPN interface, which stores a cookie each time. I also noticed the search engine is excluded from using the specified interface, which has already been reported here #3116.

[Seeker2]

Maybe qualifies as another example of this?:
qBt traffic escapes allowed interface #5272

[ngosang]

We are closing all issues related to old qBittorrent versions (qBittorrent < 4.1.0).
Please, update to last release and, if the bug/error/crash is still present, open another issue.
Thank you.