TIdFTPServer, passive mode behind NAT

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From: David Perkins
Date: Wed, 19 Sep 2007 12:14

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I have a small app that uses TIdFTPServer with no bindings.  It's behind 
NAT on IP 192.168.1.5.  I've forwarded ports 20/21.

I'm trying to use passive mode to connect to the server from an external 
IP, but it fails.  The external connection is told to connect to 
192.168.1.5,20 which it cannot.

So, I have overridden OnPASV and assigned:

   VIP = "a.b.c.d";
   VPort = m_pFtpServer->DefaultDataPort;

Where a.b.c.d is my router IP (WAN) address.  When I then attempt to 
connect I get an error: "550 Cannot assign requested address."


Q. Any idea why this error occurs?

Q. If I do not assign the VPort, would one be assigned by default?  How 
would I specify a range of Ports it could choose from - by modifying a 
TIdSocketHandle.ClientPortMax/Min?


Using BCB2006, Indy v9

Thanks

David

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