Cannot connect to IIS FTP server behind ISA since last update

[Rich C]

I just updated to the latest version, 3.2.4.1 and now cannot connect to an IIS FTP server protected by a Windows ISA firewall.

This worked before the update, it fails just after MLSD

Status: Resolving address of ftp.useast.com
Status: Connecting to 173.9.87.33:21...
Status: Connection established, waiting for welcome message...
Trace: CFtpControlSocket::OnReceive()
Response: 220 Welcome to USEast Technologies FTP site!
Trace: CFtpControlSocket::SendNextCommand()
Command: USER anonymous
Trace: CFtpControlSocket::OnReceive()
Response: 331 Password required for anonymous
Trace: CFtpControlSocket::SendNextCommand()
Command: PASS
Trace: CFtpControlSocket::OnReceive()
Response: 230 Logged on
Trace: CFtpControlSocket::SendNextCommand()
Command: SYST
Trace: CFtpControlSocket::OnReceive()
Response: 215 UNIX emulated by FileZilla
Trace: CFtpControlSocket::SendNextCommand()
Command: FEAT
Trace: CFtpControlSocket::OnReceive()
Response: 211-Features:
Response: MDTM
Response: REST STREAM
Response: SIZE
Response: MLST type*;size*;modify*;
Response: MLSD
Response: UTF8
Response: CLNT
Response: MFMT
Response: 211 End
Status: Connected
Trace: CFtpControlSocket::ResetOperation(0)
Trace: CControlSocket::ResetOperation(0)
Status: Retrieving directory listing...
Trace: CFtpControlSocket::SendNextCommand()
Trace: CFtpControlSocket::ChangeDirSend()
Command: PWD
Trace: CFtpControlSocket::OnReceive()
Response: 257 "/" is current directory.
Trace: CFtpControlSocket::ResetOperation(0)
Trace: CControlSocket::ResetOperation(0)
Trace: CFtpControlSocket::ParseSubcommandResult(0)
Trace: CFtpControlSocket::ListSubcommandResult()
Trace: CFtpControlSocket::SendNextCommand()
Trace: CFtpControlSocket::TransferSend()
Command: TYPE I
Trace: CFtpControlSocket::OnReceive()
Response: 200 Type set to I
Trace: CFtpControlSocket::TransferParseResponse()
Trace: CFtpControlSocket::SendNextCommand()
Trace: CFtpControlSocket::TransferSend()
Command: PASV
Trace: CFtpControlSocket::OnReceive()
Response: 227 Entering Passive Mode (173,9,87,33,221,78)
Trace: CFtpControlSocket::TransferParseResponse()
Trace: CFtpControlSocket::SendNextCommand()
Trace: CFtpControlSocket::TransferSend()
Command: MLSD
Trace: CFtpControlSocket::OnReceive()
Response: 550 Access is denied.
Trace: CFtpControlSocket::TransferParseResponse()
Trace: CFtpControlSocket::ResetOperation(2)
Trace: CControlSocket::ResetOperation(2)
Trace: CFtpControlSocket::ParseSubcommandResult(2)
Trace: CFtpControlSocket::ListSubcommandResult()
Trace: CFtpControlSocket::ResetOperation(2)
Trace: CControlSocket::ResetOperation(2)
Error: Failed to retrieve directory listing
Trace: CFtpControlSocket::OnReceive()
Response: 421 Connection timed out.
Trace: Unexpected reply, no reply was pending.
Trace: CRealControlSocket::OnClose(0)
Error: Connection closed by server
Trace: CFtpControlSocket::ResetOperation(66)
Trace: CControlSocket::ResetOperation(66)

[Tim Kosse]

Your ISA stuff is broken. You have to upgrade to a proper firewall.