TCP connections left open in "wait state" can cause IP DoS lockout
|Reported by:||Tom Auger||Owned by:|
|Component version:||Operating system type:|
|Operating system version:|
FileZilla appears to not be closing or reusing existing open TCP connections during download from server, relying instead on the server to time them out and close them on the remote end. For some servers that are not configured to do this within a short enough window, hundreds of TCP connections from the same IP can be manifested in a very short amount of time, often triggering an IP ban from the server (part of a DoS prevention strategy).
While I can see that this decision allows FileZilla to be really fast on downloads with a high volume of files, this does make it completely unusable for some server configurations.
Recommend making this practice optional. Provide a "reuse existing open TCP connections" option under Settings > Transfers to increase compatibility with those server configurations.