Bug 491711

SUMMARY
I am on an intranet that requires use of HTTP proxy with user authentication to access Internet resources. In my case, I only need to use the proxy for the HTTP(S) protocol. The rest of the services I access, are all local servers, which I access by the IP of each server, so they do not require the use of the proxy.

Until this last year, I have had no problems to correctly access the servers using HTTP, SMB, FTP and FISH protocols. I made myself a PAC file whose rules required to use proxy only if the request included the HTTP protocol.

However, since more than 6 months, both Dolphin and Krusader try to use the proxy ignoring the PAC file. To verify that this is a problem with the KDE libraries, I have tried other programs that allow access to FTP servers without relying on the KDE libraries, such as the following:

- “Box”, a file manager from the MATE window environment accesses the FTP server without problems.
- “Filezilla”, the FTP client by definition, seamlessly accesses the FTP server.
- “curl”, the Linux system command, seamlessly accesses the same server.

Even if I directly specify the values of these environment variables in my user's “~/.bashrc” file as follows, they are totally ignored by KIO-FTP.

export FTP_PROXY=
export ftp_proxy=
export no_proxy="0.0.0.0/0" # Don't use proxy for IPs
export NO_PROXY="0.0.0.0/0" # Don't use proxy for IPs

Despite all this, Plasma (using Dolphin or Krusader) still tries to use the proxy for any access requiring the FTP protocol, displaying the message “Could not connect to machine 10.162.0.20: The proxy type is invalid for this operation.” .

That is, Plasma Dolphin like Krusader, totally ignore the NO_PROXY / no_proxy and FTP_PROXY / ftp_proxy environment variables, regardless of whether they are specified in the system configuration, Plasma's network configuration or directly in “~/.bashrc”.


STEPS TO REPRODUCE
1. Configure proxies (any way described in summary)
2. Try to access any valid FTP local server with Dolphin or Krusader

OBSERVED RESULT
Dolphin and Krusader are unable to connect to server, they always try to use proxy.

EXPECTED RESULT
To access FTP server w/o proxy

SOFTWARE/OS VERSIONS (two distint PC and openSUSE version tested)
Operating System: openSUSE Leap 15.6  / openSUSE Leap Tumbleweed
KDE Plasma Version: 5.27.11 / 6.1.3
KDE Frameworks Version: 5.115.0 / 6.4.0
Qt Version: 5.15.12 / 6.7.2
Kernel Version: 6.4.0-150600.23.17-default (64-bit)  / 6.10.2-1-default (64-bit)
Graphics Platform: X11 / Wayland

ADDITIONAL INFORMATION
I have been using same configuration on my intranet for more than 10 years. This problem first started about 5 years ago also with FISH and SAMBA protocols, but I was able to avoid it using a local PAC file in "Use URL for proxy configuration" in Plasma "Proxy settings". 
"Caja" or "Filezilla" file manager never had this issue. Now, issue is only with FTP.