network unreachable exception

Question

Hi,

I have used the FTP library version 1.2.1 for quite a while.

Now we have a problem with one customer installation where the customer has changed his firewall setup.

What we do is a simple file upload using the FTPClient class.
When we call the put method the last logged entry is "227 Entering passive mode ...". Normally there would now appear the entry "--> STOR <filename>". But here an exception occurs with the message "network unreachable".

As I said above, I am quite sure that the customer's firewall setup is the problem. What I wonder is why I can carry out the FTP transfer manually. The client is a Windows machine and I use the built-in FTP client command line utility.

Can someone explain that to me?

Michael

Answer 1

Probably an active mode vs passive mode problem - if you change FTPClient to change modes, you'll probably find it works.

Hi,

I have used the FTP library version 1.2.1 for quite a while.

Now we have a problem with one customer installation where the customer has changed his firewall setup.

What we do is a simple file upload using the FTPClient class.
When we call the put method the last logged entry is "227 Entering passive mode ...". Normally there would now appear the entry "--> STOR <filename>". But here an exception occurs with the message "network unreachable".

As I said above, I am quite sure that the customer's firewall setup is the problem. What I wonder is why I can carry out the FTP transfer manually. The client is a Windows machine and I use the built-in FTP client command line utility.

Can someone explain that to me?

Michael

Answer 2

Thank you!

I don't know that much about FTP. I am aware that there are active and passive mode. But I thought a server would support either passive or active but not both at a time. And because the server hasn't changed, I suspected the firewall setup (which had changed definitely).

I will let you know the result.

Michael

Answer 3

Servers support both modes, firewalls cause most problems like you've described.

Thank you!

I don't know that much about FTP. I am aware that there are active and passive mode. But I thought a server would support either passive or active but not both at a time. And because the server hasn't changed, I suspected the firewall setup (which had changed definitely).

I will let you know the result.

Michael