Passive FTP problem using WinINet

Question

I'm trying to ftp a file using passive ftp but I get a timeout (12002) when the "put" command is called.

I'm able to use passive ftp with other ftp sites but not this new one.

I've tried this using three different ways on the same server: * FileZilla Client in passive mode - this works * WinINet libarary in passive mode - I get a timeout when calling PutFile * IE 6 in passive mode - I get a timeout when the directory listing is attempted

This is on a Windows 2000 server.

I assume my firewall is set up correctly since FileZilla worked.

Can anyone help me figure out what's going on?

Thank you

Answer 1

In Passive mode, the FTP server opens a port on its end and tells the FTP client the IP/Port it needs to connect to. On the client end, it creates a new socket, binds it to a local IP/Port (usually a random IP/Port unless configured otherwise), and connects to the server's specified IP/Port. Without actually seeing a trace log from a network packet sniffer, like Wireshark, then I would guess that either a firewall/router on the client end is blocking the outbound connection, or a firewall/router on the server end is blocking the inbound connection. The fact that FileZilla is getting through OK probably means that the IP/Port pairs on both ends of the connection happen to match all the firewall/router rules for accepting connections on both ends, whereas something in the WinInet/IE IP/Port pairs is getting rejected instead. That is a little unusual since Passive mode tends to be more firewall/router friendly than Active mode, though. Have you tried using Windows' command-line ftp.exe utility to see if it works or not? BTW, IE uses WinInet for all of its connections.