Warning: can't write entry into mtab (SFTP as an alternative?)

[capote (Marko)]

NethServer Version: 7.9
Module: Backup/WebDav

Hello,
I created a backup job to a Cloud Server (Strato HiDrive) and get this error mail.

Subject: Cron <root@ns-srv01> /sbin/e-smith/backup-data-wrapper fullbak2strato

/sbin/mount.davfs: Warning: can't write entry into mtab, but will mount the file system anyway at /etc/e-smith/events/actions/mount-webdav line 76.

What’s going on there?

Sincerely, Marko

Edit:

full log

Backup: fullbak2strato
Backup started at 2021-11-25 03:05:01
Pre backup scripts status: SUCCESS
/sbin/mount.davfs: Warning: can't write entry into mtab, but will mount the file system anyway  at /etc/e-smith/events/actions/mount-webdav line 76.
--------------[ Backup Statistics ]--------------
StartTime 1637805923.58 (Thu Nov 25 03:05:23 2021)
EndTime 1637806002.03 (Thu Nov 25 03:06:42 2021)
ElapsedTime 78.45 (1 minute 18.45 seconds)
SourceFiles 144319
SourceFileSize 44122708701 (41.1 GB)
NewFiles 199
NewFileSize 57130779 (54.5 MB)
DeletedFiles 40
ChangedFiles 229
ChangedFileSize 672043305 (641 MB)
ChangedDeltaSize 0 (0 bytes)
DeltaEntries 468
RawDeltaSize 80489592 (76.8 MB)
TotalDestinationSizeChange 71046764 (67.8 MB)
Errors 0
-------------------------------------------------

Local and Remote metadata are synchronized, no sync needed.
Last full backup date: Wed Nov 24 18:19:18 2021
No old backup sets found, nothing deleted.
Action 'backup-data-duplicity fullbak2strato': SUCCESS
Post backup scripts status: SUCCESS
Backup status: SUCCESS
Backup ended at 2021-11-25 03:06:51
Time elapsed: 0 hours, 1 minutes, 50 seconds

Disk Usage:
      Size       Used  Available     Use%
  25.43 GB   12.72 GB   12.72 GB      50%

[pike (Michael Kicks)]

Maybe Strato HiDrive has similar issues than pCloud have for WebDAV?

pCloud as WebDav backup location

With few steps free 7-8gb of disk space on web is available on subscribing pCloud. (Not providing the URL as choice). Subscribe for 4, 1gb more for an upload, 1gb more for installing the desktop client (which works far better than Google crap-a-like clients for gDrive), 1gb more for installing the mobile client (you can always use BlueStacks for emulate your own Android). Still did not try to use one-shot email address for steal more gb. Now… WebDav is part of pCloud. You need the right URL (…

And now i see that i should whip myself for posting screenshot in italian.

Full disclosure: with Box.com Webdav works flawleslly. With pCloud sometimes the source come validated, but backup quite never works.

[capote (Marko)]

Hi @pike
I only switched to Strato because I have the same problem with pCloud as you.
Even with the help of the pCloud support there it is not solvable, they simply claim - we have no issue, all systems work fine.

WebDAV with Strato woks fine (apart from this error message, I do not see any effects. The backup is saved well), but I’m reluctant to use WebDAV, I’d much rather use SFTP. However, SFTP does not come up, although a connection with a smp,en ftp client works.

@pagaille had comparible issues and wrote

Nethserver-backup : SFTP connectivity validation fails

Thanks Andre. But I think that the problem is clear : Nethserver’s backup module expects the target server to be smart and will not work with dumb, basic, passive, restricted, pure (S)FTP servers. I tried other ways. SMB + Restic don’t work, because of some unexplained incompatibility. I also tried Webdav + rync. Works more or less but performance is absolutely terrible, not usable. Still finding my way but generally it looks like nethserver’s backup module is not really effective with dumb a…

But I can’t interpret what “Nethserver’s backup module expects the target server to be smart and will not work with dumb, basic, passive, restricted, pure (S)FTP servers” means to confront Stratos Support with concrete requirements in their SFTP server.

Box.com isn’t an alternative.

Edit.: sorry, I just realize that I have moved from the WebDAV problem to the SFTP problem.

[pike (Michael Kicks)]

I’ve some 50GB free accounts on box.com since ages, exploiting some “promotions” launched when iOS was not having box.net app. The service could be suitable for the size and speed, but price is not that interesting.

I’ve also nudged cubbit.io for adding WebDAV access for the service. Hope that someone will nudge them soon for implement the protocol on their nice infrastructure.

[capote (Marko)]

May be related to this issue: Sftp chroot is needed?

[capote (Marko)]

And I can’t judge if that would really be the solution I should apply

SFTP chroot howto

If anybody needs to lock (chroot) an SFTP user to his own folder I did it like this (might be improved) After having enabled ShellOverrideStatus (while i’m unsure that’s needed actually) : Create chrooted group and assign it to an user. mkdir -p /etc/e-smith/templates-custom/etc/ssh/sshd_config/ nano /etc/e-smith/templates-custom/etc/ssh/sshd_config/69chrootedSFTP add the following contents : match Group chrooted@yourdomain.tld ChrootDirectory /var/lib/nethserver/home/ ForceCommand in…

[capote (Marko)]

Sorry, I just realize that I have moved from the WebDAV problem to the SFTP problem. It seems a bit confusing

[pagaille (Matthieu Gaillet)]

@capote

But I can’t interpret what “Nethserver’s backup module expects the target server to be smart and will not work with dumb, basic, passive, restricted, pure (S)FTP servers” means to confront Stratos Support with concrete requirements in their SFTP server.

I mean that NS tries to log in the server through SSH and launch some shell commands before going to SFTP. That implies that the storage is “smart” and allows that, which is not the case for most storage offers I believe.

[capote (Marko)]

@pagaille

which is not the case for most storage offers I believe.

…and with your suggestion SFTP chroot howto you can work around the problem and still use such servers?
I believe not, because I have to use credentials from the remote server.

[pagaille (Matthieu Gaillet)]

Nope : that howto was server side (NS side), to lock a distant SFTP user into a home folder. Here the problem is storage side, which doesn’t offer features or rights that the NS client expects.

[dnutan (Marc)]

The warning is nothing to be concerned about. If a newer version of davfs2 package makes its way into CentOS it will be resolved. More info at:
https://savannah.nongnu.org/bugs/?func=detailitem&item_id=58138#options

[pike (Michael Kicks)]

FWIW, current version of davfs2 installed on a fully updated NethServer davfs2-1.4.7-6.el7.x86_64

[capote (Marko)]

it seems that centos7 has to be updated since 2020

You might try a newer version of davfs2, e.g. 1.5.6. It will be able to handle situations where /etc/mtab is a symbolic link to a kernel file system and not writable.

[pike (Michael Kicks)]

Maybe is the “usual” management of CentOS: only patches/updates, not “upgrades”.

[dnutan (Marc)]

On CentOS 8 you have 1.5.6 but not on CentOS 7 (which is more or less like this since I coded the webDAV support for backups).

[robb (Rob Bosch)]

Maybe another webdav provider? I use stack from transip (transip.nl/stack). Unfortunately their website in currently only available in Dutch, but with Goole translate it should be possible to get the idea of what it is and does.
I use it with WebDav for over 4 years now as backup location for my NethServer based VPS’s
ps: when you have an account, you can change the interface into English…

[pagaille (Matthieu Gaillet)]

Dutch isn’t an issue I’m Belgian

Good pointer I will have a look !

[pike (Michael Kicks)]

@robb

Unfortunately their website in currently only available in Dutch,

@pagaille

Dutch isn’t an issue I’m Belgian

IDK which people loves more beer among these two…

[capote (Marko)]

@robb

I use stack from transip (transip.nl/stack).

That looks good, I will book it. I live 50 km from the Dutch border, in the Ruhrgebiet.

Thank you, Marko

[capote (Marko)]

@robb

when you have an account, you can change the interface into English…

Thank for the hint…can you point me, please? Perhaps I’m blind