Re: Problems with active FTP via ISA 2004 proxy

Giganews Newsgroups
Subject: Re: Problems with active FTP via ISA 2004 proxy
Posted by:  Remy Lebeau (TeamB) (
Date: Thu, 2 Feb 2006

"Toby Groves" <> wrote in message

> Using TIdFTP (Indy 10) however, passive works fine but active does
> not.

Which build of Indy 10 are you using?

> Tracing it through, I can see that in the TIdFTP.InternalGet
> procedure, the BoundIP property of the LPortSv listener socket
> is being set to the external IP of the proxy server.

That is wrong.  The BoundIP must be set to the IP of the local machine, not
the proxy server.  The IP that is transmitted in the PORT command has to be
the proxy server's IP, however.  TIdFTP has an ExternalIP property for that
purpose.  If your copy of Indy 10 does not have the ExternalIP property,
then you need to upgrade.

> Unfortunately, when I get to the LPortSv.Listen command, it
> throws an EIdNotASocket error, as it's obviously trying to bind
> to an IP address which doesn't exist on the client computer.

Correct.  In the build of Indy 10 that has the ExternalIP property
available, the TIdSimpleServer is always bound to the local machine
unconditionally, so that exception will not happen (You will still get an
exception if the local port is in already use, though).



In response to

Problems with active FTP via ISA 2004 proxy posted by Toby Groves on Thu, 02 Feb 2006