Re: [webmin-l] Issue with backing up *via ssh* from a Linux system to a NetBSD system using the "Filesystem Backup" module

[Christopher P. <cj...@ex...>]

Le 2022-10-16 22:38, Patrick Shoaf a écrit :
> On 10/16/22 14:55, Christopher Pinon wrote:
>> Le 2022-10-16 19:24, Jamie Cameron a écrit :
>>> On 16/Oct/2022 03:59 Christopher Pinon <cj...@ex...> wrote ..
>>>> Le 2022-10-16 07:53, Jamie Cameron a écrit :
>>>> > On 15/Oct/2022 11:58 Christopher Pinon <cj...@ex...> wrote ..
>>>> >> Le 2022-10-15 18:49, Jamie Cameron a écrit :
>>>> >> > On 15/Oct/2022 06:30 Christopher Pinon <cj...@ex...> wrote ..
>>>> >> >> Hi,
>>>> >> >>
>>>> >> >> I've been using Webmin for a few years and am currently using v. 2.000
>>>> >> >> .
>>>> >> >>
>>>> >> >> I've noticed a significant issue with backing up *via ssh* from a
>>>> >> >> Linux
>>>> >> >> system to a NetBSD system using the "Filesystem Backup" module. In
>>>> >> >> fact,
>>>> >> >> this is an issue that I've always experienced with Webmin, but I
>>>> >> >> thought
>>>> >> >> that I would finally ask about it. :-)
>>>> >> >>
>>>> >> >> First of all, backing up *via ftp* from Linux to NetBSD works fine
>>>> >> >> (whether by dump or by tar), and this is what I've been doing.
>>>> >> >>
>>>> >> >> However, backing up *via ssh* from Linux to NetBSD doesn't work for
>>>> >> >> some
>>>> >> >> reason. If I start a backup from Linux to NetBSD, the process begins
>>>> >> >> and
>>>> >> >> takes a long time and finally gives up (or after a long time, I give
>>>> >> >> up
>>>> >> >> and terminate the process). There's never ever any trace of the dump
>>>> >> >> or
>>>> >> >> tar file on the NetBSD system.
>>>> >> >>
>>>> >> >> (As a sanity check, backing up via ssh from Linux to Linux *does* work
>>>> >> >> for me.)
>>>> >> >>
>>>> >> >> Naturally, ssh/sftp work fine on the NetBSD system -- after all, it's
>>>> >> >> (standard) OpenSSH.
>>>> >> >>
>>>> >> >> Webmin doesn't display any error message, as far as I can tell: the
>>>> >> >> backup process simply doesn't succeed after a long while. None of the
>>>> >> >> files miniserv.error , miniserv.log , or webmin.log seems to indicate
>>>> >> >> that anything went wrong, as far as I can tell.
>>>> >> >>
>>>> >> >> I wanted to ask: is this a known issue? Where could I look for the
>>>> >> >> source of the error?
>>>> >> >>
>>>> >> >> I'd be grateful for any advice.
>>>> >> >
>>>> >> > Hi Christopher,
>>>> >> >
>>>> >> > Are you using a password to authentication via SSH to the remote
>>>> >> > system,
>>>> >> > or a private key? Also, can you SSH with the same credentials from the
>>>> >> > command line on your Webmin system?
>>>> >> >
>>>> >> >  - Jamie
>>>> >>
>>>> >> Hi Jamie,
>>>> >>
>>>> >> I'm using a password to authenticate via ssh on the remote (NetBSD)
>>>> >> system. (All of my backup tests via ssh with Webmin from Linux to
>>>> >> NetBSD
>>>> >> and from Linux to Linux have used a password to authenticate.)
>>>> >>
>>>> >> On the command line of the Linux system (where Webmin is installed), I
>>>> >> can use ssh/sftp/scp to reach my account on the remote NetBSD system.
>>>> >> In
>>>> >> fact, I've just tried all three of these commands and they work!
>>>> >>
>>>> >> Even so, any attempt to use the "Filesystem Backup" module of Webmin
>>>> >> on
>>>> >> the Linux system to back up via ssh a (small) directory to the NetBSD
>>>> >> system fails. Basically, the process takes many-many minutes -- it
>>>> >> seems
>>>> >> to hang -- before it finally gives up (or I kill it), with absolutely
>>>> >> no
>>>> >> result.
>>>> >>
>>>> >> In contrast, choosing to use ftp in the module works fine.
>>>> >>
>>>> >> I've experienced this issue since I began to use Webmin, which was
>>>> >> around four years ago.
>>>> >
>>>> > Hi Christopher,
>>>> >
>>>> > What if you backup from your Linux system to a different Linux system,
>>>> > rather than NetBSD? That would be a useful test to figure out if the
>>>> > issue is coming from the client or server side..
>>>> >
>>>> >  - Jamie
>>>> 
>>>> Hi Jamie,
>>>> 
>>>> Yes, backing up (via ssh in the Webmin module) from the Linux system 
>>>> to
>>>> a different Linux system works fine. I've just tested this again.
>>>> 
>>>> But again, backing up (via ssh in the Webmin module) from the same 
>>>> Linux
>>>> system to the NetBSD system doesn't work. In fact, I've just tried 
>>>> to
>>>> back up to two different NetBSD systems, and neither works. In 
>>>> contrast,
>>>> backing up via ftp works.
>>>> 
>>>> I'd agree that it looks like NetBSD is the problem here, but at the 
>>>> same
>>>> time, on both (up-to-date) NetBSD systems, we're talking about
>>>> garden-variety sshd (from OpenSSH) with barely any custom 
>>>> configuration
>>>> (the only customized change is that X Forwarding has been turned 
>>>> on).
>>>> Add to this that I can ssh/sftp/scp on the command line from the 
>>>> Linux
>>>> system to either NetBSD system without difficulty.
>>>> 
>>>> So it's a puzzle to me. In addition, as I said in my initial message
>>>> (above), Webmin doesn't provide any error message in this case: the
>>>> process just seems to fall into a loop and to take a very long time. 
>>>> On
>>>> my most recent attempt, the circle for "Save and Backup Now" is 
>>>> still
>>>> spinning without any error message after more than an hour, whereas 
>>>> a
>>>> backup via ftp of the same small directory takes less than 10 
>>>> seconds.
>>> 
>>> Does the "rmt" command exist on your NetBSD system, and if so in what
>>> location? I seem to recall that it's different from on Linux, and 
>>> this can
>>> cause remote tar backups to fail because the tar command expects to 
>>> be
>>> able to run it.
>> 
>> Yes, in fact, I had already looked into this. rmt is indeed present 
>> (by default) on NetBSD, and its path is the same as on my Linux 
>> systems: /usr/sbin/rmt . So my conclusion was that this wasn't an 
>> obstacle.
>> 
>>>> P.S.: If you would like to try to replicate this issue, I'd be happy 
>>>> to
>>>> give you a temporary shell account on one of the NetBSD systems. I 
>>>> often
>>>> wonder whether I'm missing something obvious, which is possible, 
>>>> despite
>>>> my numerous tests/attempts (which is also why I hesitated to write 
>>>> to
>>>> the mailing list). :-(
>>> 
>>> Sure, that would be useful! You can contact me off-list with the 
>>> details ..
>> 
>> I'll send you the details to your webmin address within 15 minutes. 
>> Thanks for being willing to look into this. If it works for you right 
>> away, I may need to seriously question my sanity! :-D
>> 
>> C.

Hi Patrick,

> I just installed a NetBSD 9.3 virtual machine and tried using the
> filesystem backup and have the same problem with ssh.

Thanks a lot for your independent confirmation of this. :-)

> rmt is located in 2 locations /etc/rmt and /usr/sbin/rmt. /etc/rmt is
> a link to /etc/sbin/rmt.

You mean a link to /usr/sbin/rmt (not to /etc/sbin/rmt ), right? :-)

I guess that the link /etc/rmt is there for compatibility purposes. 
"type rmt" will give /usr/sbin/rmt .

C.