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IIS FTP through port forwarding, passive mode problem

Last response: in Networking
December 6, 2006 8:13:53 AM

Hi guys,

I'm trying to run an IIS FTP site through a port forwarding router (BEFSR41). All ports are forwarded to my server at but passive mode doesn't work.

IIS seems to be sending an incorrect IP for passive mode (it's using the local IP rather then the internet ip)

227 Entering Passive Mode (192,168,0,10,18,106).

I can't run active ftp as the machine I'm FTPing from is also behind a router

Is there any way to configure IIS to get round this?
December 6, 2006 10:52:32 AM

Nope I'm testing from a remote PC using the internet IP for my router.

I can make an ftp connection to port 21 fine, it just fails when setting up the data connection

The FTP test returned

* About to connect() to x.x.x.x port 21
* Trying x.x.x.x ... connected
* Connected to x.x.x.x (x.x.x.x ) port 21
< 220 Microsoft FTP Service

> USER guest
< 331 Password required for guest.

> PASS *****
< 230 User guest logged in.

< 257 "/guest" is current directory.
* Entry path is '/guest'

> CLNT Testing from from IP
< 500 'CLNT Testing from from IP': command not understood
* QUOT command failed with 500
* Connection #0 to host x.x.x.x left intact

* Closing connection #0

which doesn't look particularly helpful
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December 6, 2006 1:21:26 PM

All ports are being forwarded (1 to 65535)

One thing I noticed is the ftp program is sending "227 Entering Passive Mode (192,168,0,10,18,106)". which is the LAN address rather then the external address.

Do FTP clients use this IP or will they go with the original host name given?
December 6, 2006 2:23:46 PM

Can't answer your question. I've never setup a FTP server using IIS.

January 10, 2007 8:28:49 PM

when you run your FTP server in passive mode, the server needs to send the client a response with the external IP address i think. If the FTP server sends the internal IP as the response then things wont work. this is usually configurable on the server. if you can't figure it out with IIS, then I dont blame you. Try using FileZilla FTP Server because its easier to understand I think and that configuration parameter is easy to find.
January 10, 2007 9:53:12 PM

Setting up FTP servers can be a royal pain. I have setup several FTP server, both NAS boxes. One worked with out a hitch, the other was browser sensitive. I had one that only worked with IE passing the user & pw on the address bar. The problem accours when there are firewalls on both ends.

Here is a link that will help explain how the hand shaking works.

Good luck.
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