I have ISA 2006 going to a win2k3 server. I was able to setup an ftp site quite easily on port 21. But, I need to have additional ftp sites on the same IP. I setup the second ftp server on the win2k3 server easily and got it running. I have different welcome messages for each ftp site, so I know for sure which one I'm hitting. I tried to publish the second ftp site on alternate port (currently using 99). In ISA, it's listening on port 99 and forwarding the requests to port 99 on the win2k3 server. In viewing the log file on my ftp client, I'm able to see that it's hitting the ftp site on port 99 for login and gets past that. When the ftp client tries to run the port command, I get "invalid port command", which is coming from the ISA server, not the win2k3 server. I checked the ftp logs on the server and can see the authentication requests getting through, but nothing about the invalid port command, which seems to be coming directly from ISA 2006 server.
Any ideas on what I need to do to allow this second ftp server on ISA 2006 to get past the invalid port command error?