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FTP file upload through proxy API function

FTP file upload through proxy API function

FTP file upload through proxy API function

Hi, I've written an application for a Windows client that is behind a ISA-server (Microsoft Internet Security and Acceleration Server). Now this client has to upload some files to a FTP server outside the ISA server, doing so the client has to use the standard proxy-server installed by default on the ISA server to connect to the Internet where this FTP server is living.

The question now is what windows API should I use? When there is no proxy server between I use from the wininet.dll the InternetOpen, InternetConnect and FtpPutFile functions. But I can't figure out what functions I should use to go through the proxy server, can I use the same functions, but what about the parameters than? Or other functions?

Any help or point into the right direction is helpful!

Thanks in advance,

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RE: FTP file upload through proxy API function

Hi RedLion,

I'm no expert, but I took a quick look at the ISA webpage and noticed that there is a (free) client that you can install which evidently handles FTP through the proxy and allows applications to work as if the proxy was not there. Another thought is to try passive FTP, which I read that WinInet supports via the InternetOpenURL function with the INTERNET_FLAG_PASSIVE parameter. I vaguely recall I was able to use passive FTP (PASV) to get through a SOCKS proxy (some years ago, memory is faulty). Just suggestions in case you have not tried these things.

Good Luck,


RE: FTP file upload through proxy API function

Hi Greg,

Thanks for your quick response! I was a week off, but I'm back on the job.

About the client proxy, the problem is that the application is running on a Terminal server, so I have to look what problems that gives with the server engineers who are running the Terminal servers. Life is a bitch if you can't control everything yourself winky smile
And passive didn't the trick for me either...

So if I can use the client proxy I'm saved, but otherwise...

At least thanks, and if you came up with other suggestions in the meanwhile I love to hear them!


RE: FTP file upload through proxy API function

I am not allowed to use the proxy client...sad

One of the reasons is that other programs they have installed are successfully using the proxy...so I should be able to do it to.

So any help or ideas are welcome!!!

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