This issue has been added to the tracker:
https://winscp.net/tracker/1266

You can workaround the problem by resetting session setting Force IP address for passive mode connections back to the default Auto.

I'd like to fix this anyway. I have sent you an email with a debug version of WinSCP to address you have used to register on this forum.

I am trying to get my WinSCP (Windows 2012 R2) to connect to my vsFTP instance through my Squid proxy. As far as I can determine I have things configured correctly. If I use FireFox and go to the FTP address (FTP proxy information supplied to FireFox) it connects and brings back the correct directory listing. I just don't seem to be able to get my WinSCP GUI client to behave correctly.

My vsFTP instance is at 172.16.13.123 and my Squid instance is at 10.1.50.67.


This is my log from my latest WinSCP attempt

. 2015-01-06 16:13:08.797 --------------------------------------------------------------------------
. 2015-01-06 16:13:08.797 WinSCP Version 5.5.6 (Build 4746) (OS 6.3.9600 - Windows Server 2012 R2 Standard)
. 2015-01-06 16:13:08.797 Configuration: HKEY_CURRENT_USER\Software\Martin Prikryl\WinSCP 2\
. 2015-01-06 16:13:08.798 Local account: Domain\JohnDoe
. 2015-01-06 16:13:08.798 Working directory: C:\Program Files (x86)\WinSCP
. 2015-01-06 16:13:08.798 Process ID: 4404
. 2015-01-06 16:13:08.798 Command-line: "C:\Program Files (x86)\WinSCP\WinSCP.exe"
. 2015-01-06 16:13:08.798 Time zone: Current: GMT-5, Standard: GMT-5 (Eastern Standard Time), DST: GMT-4 (Eastern Daylight Time), DST Start: 3/8/2015, DST End: 11/1/2015
. 2015-01-06 16:13:08.798 Login time: Tuesday, January 6, 2015 4:13:08 PM
. 2015-01-06 16:13:08.798 --------------------------------------------------------------------------
. 2015-01-06 16:13:08.798 Session name: RHEL_FTP (Site)
. 2015-01-06 16:13:08.798 Host name: 172.16.13.123 (Port: 21)
. 2015-01-06 16:13:08.798 User name: dilbert (Password: Yes, Key file: No)
. 2015-01-06 16:13:08.798 Tunnel: No
. 2015-01-06 16:13:08.798 Transfer Protocol: FTP
. 2015-01-06 16:13:08.798 Ping type: C, Ping interval: 30 sec; Timeout: 15 sec
. 2015-01-06 16:13:08.798 Proxy: HTTP
. 2015-01-06 16:13:08.798 HostName: squid.xyz.net (Port: 3128); Username: ; Passwd: No
. 2015-01-06 16:13:08.798 Send buffer: 262144
. 2015-01-06 16:13:08.798 UTF: 2
. 2015-01-06 16:13:08.798 FTP: FTPS: None; Passive: Yes [Force IP: +]; MLSD: A [List all: A]
. 2015-01-06 16:13:08.798 Local directory: E:\JohnDoe\uftp_exe_W7-4.6, Remote directory: /, Update: Yes, Cache: Yes
. 2015-01-06 16:13:08.798 Cache directory changes: Yes, Permanent: Yes
. 2015-01-06 16:13:08.798 DST mode: 1; Timezone offset: 0h 0m
. 2015-01-06 16:13:08.798 --------------------------------------------------------------------------
. 2015-01-06 16:13:08.863 Connecting to 172.16.13.123 ...
. 2015-01-06 16:13:08.863 Proxy layer changed state from unconnected to connecting
. 2015-01-06 16:13:08.863 Proxy layer changed state from connecting to connected
. 2015-01-06 16:13:08.915 Connected with 172.16.13.123. Waiting for welcome message...
< 2015-01-06 16:13:08.915 220 (vsFTPd 3.0.2)
> 2015-01-06 16:13:08.915 USER dilbert
< 2015-01-06 16:13:08.915 331 Please specify the password.
> 2015-01-06 16:13:08.915 PASS **********
< 2015-01-06 16:13:08.982 230 Login successful.
> 2015-01-06 16:13:08.982 SYST
< 2015-01-06 16:13:09.002 215 UNIX Type: L8
> 2015-01-06 16:13:09.002 FEAT
< 2015-01-06 16:13:09.020 211-Features:
< 2015-01-06 16:13:09.020 EPRT
< 2015-01-06 16:13:09.020 EPSV
< 2015-01-06 16:13:09.020 MDTM
< 2015-01-06 16:13:09.022 PASV
< 2015-01-06 16:13:09.022 REST STREAM
< 2015-01-06 16:13:09.022 SIZE
< 2015-01-06 16:13:09.022 TVFS
< 2015-01-06 16:13:09.022 UTF8
< 2015-01-06 16:13:09.022 211 End
> 2015-01-06 16:13:09.022 OPTS UTF8 ON
< 2015-01-06 16:13:09.041 200 Always in UTF8 mode.
. 2015-01-06 16:13:09.067 Connected
. 2015-01-06 16:13:09.067 Got reply 1 to the command 1
. 2015-01-06 16:13:09.067 --------------------------------------------------------------------------
. 2015-01-06 16:13:09.067 Using FTP protocol.
. 2015-01-06 16:13:09.068 Doing startup conversation with host.
> 2015-01-06 16:13:09.118 PWD
< 2015-01-06 16:13:09.138 257 "/"
. 2015-01-06 16:13:09.138 Got reply 1 to the command 16
. 2015-01-06 16:13:09.169 Changing directory to "/".
> 2015-01-06 16:13:09.170 CWD /
< 2015-01-06 16:13:09.189 250 Directory successfully changed.
. 2015-01-06 16:13:09.189 Got reply 1 to the command 16
. 2015-01-06 16:13:09.189 Getting current directory name.
> 2015-01-06 16:13:09.189 PWD
< 2015-01-06 16:13:09.207 257 "/"
. 2015-01-06 16:13:09.207 Got reply 1 to the command 16
. 2015-01-06 16:13:09.371 Retrieving directory listing...
> 2015-01-06 16:13:09.371 TYPE A
< 2015-01-06 16:13:09.371 200 Switching to ASCII mode.
> 2015-01-06 16:13:09.371 PASV
< 2015-01-06 16:13:09.371 227 Entering Passive Mode (172,16,13,123,250,64).
. 2015-01-06 16:13:09.371 Error retrieving server address
. 2015-01-06 16:13:09.371 Could not retrieve directory listing
. 2015-01-06 16:13:09.371 Got reply 4 to the command 2
. 2015-01-06 16:13:09.372 LIST with -a failed, will try pure LIST
. 2015-01-06 16:13:09.422 Retrieving directory listing...
> 2015-01-06 16:13:09.422 TYPE A
< 2015-01-06 16:13:09.422 200 Switching to ASCII mode.
> 2015-01-06 16:13:09.422 PASV
< 2015-01-06 16:13:09.422 227 Entering Passive Mode (172,16,13,123,250,148).
. 2015-01-06 16:13:09.422 Error retrieving server address
. 2015-01-06 16:13:09.422 Could not retrieve directory listing
. 2015-01-06 16:13:09.422 Got reply 4 to the command 2
* 2015-01-06 16:13:09.522 (ECommand) Error listing directory '/'.
* 2015-01-06 16:13:09.522 Error retrieving server address
* 2015-01-06 16:13:09.522 Could not retrieve directory listing
. 2015-01-06 16:13:10.893 Startup conversation with host finished.
. 2015-01-06 16:13:11.611 Session upkeep
. 2015-01-06 16:13:12.112 Session upkeep
. 2015-01-06 16:13:12.614 Session upkeep
. 2015-01-06 16:13:13.115 Session upkeep
. 2015-01-06 16:13:13.603 Session upkeep
. 2015-01-06 16:13:14.104 Session upkeep
. 2015-01-06 16:13:14.603 Session upkeep
. 2015-01-06 16:13:15.104 Session upkeep
. 2015-01-06 16:13:15.228 Got reply 1004 to the command 2
. 2015-01-06 16:13:15.228 Disconnected from server