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FTP 550 Error - Port Related? Rights are fine.

I have a user in another companies network. They can log into my FTP server fine. They are getting an FTP 550 error when they try a put or a get. If I log in from the internal network with the user's ID and password I am able to make a put or get. I have tried the FTP Server from Win2000 and Solaris 8, and used both IE and command line as a client. Works from inside the network, but not outside.

Could this be a port issue? I have opened port 20 and 21 in the firewall between the two companies.

Could it be a PASV issue where the FTP server is trying to use a higher port not allowed through the firewall?

Any help would be great.

1 Solution
Is the remote user accessing  the FTP server through a firewall at their end (i.e. they are behind a firewall)? If so, they should use PASV mode. Normal mode FTP is weird in that the client connects to the server, but then the server drops that connection and initiates a connection back to the client. Seeing as most firewalls don't like connections initiated from outside, this tends to fail. Passive mode (PASV) keeps the session as a truly client to server conversation- firewall sees the connection go out, makes a note of it in its' state table (if it's a stateful inspection FW), and all is cool.

This may not be the solution to your problem, but PASV is always recommended when passing through a firewall.
p1800volvoAuthor Commented:
If I had to bet it is a PIX firewall.

I will try PASV. Hopefully that will work.

Hi all,

I got exactly the same problem with FielZilla (FTP client).
I behind NAT and since port 21 was propely forwarded; I had the same firewall as before the NAT implementation so I thought the issue was related to NAT.

I was constantly getting the message:

Response:      550 Data connection must go to same host as control connection.
Error:      Disconnected from server
Error:      Could not retrieve directory listing
Error:      Timeout detected!

After reading this post, I've simply enabled the passive mode in FileZilla and ...

Response:      150 Data connection accepted from xx.xxx.xx.xxx:xxxx; transfer starting.
Response:      226 Listing completed.
Status:      Directory listing successful


thanks for the solution and I hopethis will help others as well...

have a nice day

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