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iis ftp : Multiple FTP sites problem


Elie Grouchko
6/8/2006 8:20:48 PM
Hi All

I tried to setup the following configuration of 2 FTP sites:

1. Default FTP site, port 21, no user isolation, read + write.
2. 2nd FTP site (same IP as the first), port 7721, users isolated (no AD),
read only.

The second site returns an error (from the Windows explorer) when I try to
access it using the following URL:
ftp://user:1234@212.212.212.212:7721/

The error I get is:
And error occurred opening that folder on the FTP Server. Make sure you have
permission to access that folder
Details:
200 Type set to A
500 Invalid PORT Command
500 'LPRT 6,16,0,0,0,0,0,0,0,228,241,7,4,0,0,0,0,2,8,25`: command not
understood

If I shutdown the first site, and change the port of the second site to 21,
it works fine, so I assume it has to do with the port number. I looked for
information on using different port numbers for multiple FTP sites, but
didn't find anything on such a problem.

Help will be greatly appreciated

Thanks

Elie Grouchko

Bernard Cheah [MVP]
6/9/2006 12:00:00 AM
As you may have noticed.. this article explains why.
FTP Error: 500 Invalid PORT Command
http://support.microsoft.com/?id=281193

--
Regards,
Bernard Cheah
http://www.iis.net/
http://www.iis-resources.com/
http://msmvps.com/blogs/bernard/


[quoted text, click to view]

Robin Walker [MVP]
6/9/2006 10:29:10 AM
[quoted text, click to view]

You dont'say, but I'm guessing that your FTP client is running behind a NAT
router. NAT routers at the client end cannot handle Active Mode FTP
correctly unless they specially recognise it, and they recognise an FTP
connection by a TCP connection being made to remote port 21. Therefore
client-side NAT routers fail to handle Active Mode FTP conenctions to ports
other than 21.

This is not an FTP server issue. It is an issue with the NAT box at the
client end in particular, and an issue with the FTP protocol in general.

--
Robin Walker [MVP Networking]
rdhw@cam.ac.uk

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