Passive mode not honoring first connection IP when using proxy
|Reported by:||miguel.g757||Owned by:|
|Keywords:||ftp passive nat||Cc:|
|Component version:||3.53.1||Operating system type:||Windows|
|Operating system version:||10|
I'd like to understand if this is a bug - it does very much look like one to me.
Scenario: FTP server behind NAT
Behavior without proxy:
When using FTP passive mode, and the server replies with its real IP address, Filezilla ignores it, uses the original IP instead, and uses the port for data connection. This is absolutely correct.
Behavior with proxy:
When using FTP passive mode, and the server replies with its real IP address, Filezilla send a new request to the proxy but uses the server reply. The proxy tries to contact the server's real IP, and (in most scenarios) fails.
I found this issue with FTPS, not plain FTP, but the implementation might be the same. It doesn't help that the traffic is encrypted, otherwise I could have found some workaround. But with encrypted traffic I have no chance to do so.