Error: 425 Can't Open Data Connection..

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kwriley87
500 Command not understood
Posts: 4
Joined: 2018-10-11 16:15

Error: 425 Can't Open Data Connection..

#1 Post by kwriley87 » 2018-10-11 16:24

Hello-

I am running Filezilla server on Windows with a Vultr instance and am trying to FTP a file from a Linux server to my FTP server however I am receiving an error 425 can't open data connection on the server when the file is attempting to be transferred.

A few facts:
I've defined the passive ports in Filezilla server from 50000-50100
The external server is configured for the public IP of my server
Ports 50000-50100 are opened on the firewall of my Vultr instance AND Windows Firewall

When watching the incoming connection, it looks like the incoming port isn't in the range of what I've opened up that is 50000-50100 instead from the example attached, it looks to be coming in on port 54653 (213*256+125)
I'm guessing that's why this isn't working but I'm not sure how to control the incoming port to be in line of the opened passive ports of 50000-50100 on the Filezilla server.

Can anyone help me out?
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boco
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Location: Germany

Re: Error: 425 Can't Open Data Connection..

#2 Post by boco » 2018-10-11 17:33

The client is using Active mode, not Passive mode (which you configured your ports for). The PORT command is used only with Active mode, Passive uses PASV.

The data port you calculated is located at the client's side, not yours. The client has to configure his/her network and FTP client, to accept incoming connections on his/her data ports. If that isn't desired/possible, the client MUST use Passive mode (neither the ftp command on Windows nor Linux support Passive at all).
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kwriley87
500 Command not understood
Posts: 4
Joined: 2018-10-11 16:15

Re: Error: 425 Can't Open Data Connection..

#3 Post by kwriley87 » 2018-10-12 12:02

Hi Boco

Thanks for the reply and insight that the client is using Active, not Passive.

I'm not sure what you mean by saying the client has to accept incoming connections on his/her data ports? The client is sending the data to the server, not receiving -- why would the client side firewall matter in this scenario?

kwriley87
500 Command not understood
Posts: 4
Joined: 2018-10-11 16:15

Re: Error: 425 Can't Open Data Connection..

#4 Post by kwriley87 » 2018-10-12 12:10

Hi Boco-

Ahh on the network configuration page, my question is answered..

"In active mode, the client opens a socket on the local machine and tells its address to the server using the PORT command. Once the client issues a command to transfer a file or listing, the server will connect to the address provided by the client."

Ok fair enough.. Since the data ports are always different it seems, how would I find out what my client's data port range is so that I can open them up on the client side firewall?

kwriley87
500 Command not understood
Posts: 4
Joined: 2018-10-11 16:15

Re: Error: 425 Can't Open Data Connection..

#5 Post by kwriley87 » 2018-10-12 12:19

I know you said that the FTP command in Linux doesn't support passive but I was able to resolve my issue by using the "passive" syntax in my FTP command on my Linux client.

Strange I suppose, but it's working. Thank you.

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