FTP from a Linux machine to an RT cRIO chassis gives "Connection Refused"

[Chris_12345]

Using a Command window on a Windows machine, I can use FTP commands to access files that are on my cRIO chassis.  However, when I try to do the same thing from a Linux machine, the connection is refused. Ping works fine.  Any ideas on why the difference?

[Chris_12345]

Under SUSE 11.1 Linux, the FTP reply is "Connection refused".

[Chris_12345]

Also, I am able to FTP from one Linux machine to another Linux machine.

[Ben_S]

Chris 12345,

I'm not terribly familiar with Linux, however, one suggestion I have would be to try a different FTP client to see if for some reason the client is causing the issues and that you indeed are not doing anything wrong.

[quicknix]

I am working with Chris on this here.  This is what I am seeing.  We have one Linux machine that reliably connects to all cRIOs via FTP all the time.  Most other Linux machines cannot connect.  One that I am trying to configure to work like the other one, connects sometimes to some of the cRIOs and sometimes it is like the others (connection refused).  Is there some state or settings in the cRIO that affect the FTP server's behavior?  I cannot explain why some Linux machines are different.  The packages are almost the same on each Linux machine.  It seems like the FTP server on the cRIO is different sometimes.... ??  Is there any more information on the cRIO's FTP server?

[Ben_S]

Quicknix,

Do all of your linux machines run the same OS (SUSE 11.1 as mentioned before)? Also, can you FTP from the CompactRIO to the linux machines that don't allow you to FTP to the CompactRIO from Linux?

I'm looking for more information on the CompactRIO's FTP Server. It shouldn't be differen't if you have the same version of NI RT and NI RIO installed on the CompactRIO'.

[quicknix]

Hello Ben,

Yes, all machines are openSUSE 11.1.  I have modified one to get the ftp packages to match the one that does work reliably, but it still does not work most of the time.  Sometimes I can login with FTP, most of the time I cannot.

As I understand it, the NI-RT is the same on all CRIOs.

What is the easiest way to try FTPing out of a CRIO?  Can I login to a user shell?

Thanks,

Ken

I guess I could change my alias to Kenix...

[Ben_S]

quicknix,

I would write a program in LabVIEW Real-Time to do the FTP on the cRIO level. There isn't a user shell that you can log into to do the FTP operations.

How Can I Use LabVIEW to FTP Files to and from My Real-Time Target

Changing FTP Server Password for Real-Time Controllers

[quicknix]

Thanks Ben,

One of the guys here mentioned that already.  I am a Linux guy so building a LabView app would be on them.  I'm thinking that we could also build a LV app to run on Linux to FTP things to and fro.  This may be the only reliable way to FTP things within a Linux environment.

Another thing I noticed is that if I shut down the application that the CRIO is communicating with, I can connect via FTP within a few minutes... usually.  Then when I fire the application back up, after a few minutes I can no longer connect via FTP.... ??  It seems to have something to do with how busy it is.  Of course, FTP from a Windows command prompt works all the time with or without the app running....

[Ben_S]

quicknix,

That is strange that your application seems to block out the Linux FTP requests but not the Windows requests. You can monitor the CPU/Memory usage of your app on the CompactRIO by using the Distributed System Manager to see if you might be maxing out the CPU. This, however, wouldn't explain why the windows requests still go through.