Issue Help: Problem with FTP(S) on Ubuntu 18

[kankamuso]

Server operating system version

Ubuntu 18.04.6 LTS

Plesk version and microupdate number

Plesk Obsidian 18.0.52 Update #3

Hi, a server working for months has suddenly become unable to create remote backups to our FTP(S) server. We have other Plesk servers successfully running against that FTP server so we can rule out the remote server as a source of problems. Also, we have no firewall active on that side. The problem is that the check directories and files are created before attempting to create a new backup but the system detects that such check file/folder cannot be deleted and refuses to continue with the backup. This is only happening with a Plesk server running under Ubuntu 18. The other servers are configured used debian. Following plesk suggestions appearing on the UI after the error:


And here are my outputs:


and:



What could be going wrong here? Any help is appreciated.

Thanks in advance,
Jose

 

[Peter Debik]

Before we dive into a deeper analysis I recommend to first update Plesk to the latest version. This will fix a lot already.

 

[kankamuso]

Before we dive into a deeper analysis I recommend to first update Plesk to the latest version. This will fix a lot already.

Thanks, I forgot to update but after doing it still same problem :-(. A couple of check folders are created with a file within each and then they cannot be removed. I have tried with different NAS users and even with the administrator...

 

[Peter Debik]

We have other Plesk servers successfully running against that FTP server so we can rule out the remote server as a source of problems.

Unfortunately, no, it must be a configuration issue on the target. The reason for that is that FTP commands and transport protocol are always the same and the response is not generated by the source, but by the target FTP server. It could be a permissions issuse or an issue with limited concurrent connections to the server. The later could be mitigated by applying this setting to panel.ini of Plesk:

[pmm]
ftpForbidReuseConnection = 1

It will limit the number of concurrent connections that Plesk creates to your FTP storage. But again, if this works, it is still an indication that the target has an issue with connections.

 

[kankamuso]

Unfortunately, no, it must be a configuration issue on the target. The reason for that is that FTP commands and transport protocol are always the same and the response is not generated by the source, but by the target FTP server. It could be a permissions issuse or an issue with limited concurrent connections to the server. The later could be mitigated by applying this setting to panel.ini of Plesk:

[pmm]
ftpForbidReuseConnection = 1

It will limit the number of concurrent connections that Plesk creates to your FTP storage. But again, if this works, it is still an indication that the target has an issue with connections.

But then how is it that it can create files and folders and cannot delete them? I had already tried the ftpForbidReuseConnection = 1 flag with no luck :-(

 

[Peter Debik]

I don't know the answer, but as you can see from the log you showed, Plesk issues the DELE command. Why the target FTP server does not like it needs to be checked on the target FTP server.

 

[kankamuso]

I don't know the answer, but as you can see from the log you showed, Plesk issues the DELE command. Why the target FTP server does not like it needs to be checked on the target FTP server.

Ok, let's have a deeper look at it... Thanks a lot!