Re: Trouble running rdiff-backup after Windows updates

I sent this privately to Eric by mistake, now replying on list.

Hi Eric,

Answers inline below.

On 11/1/21 1:22 PM, Eric L. Zolf wrote:
> Hi Michael,
>
> it's difficult to tell without a more concrete error message. Running
> the command in debug mode (-v 9) might help to understand where the
> script hangs.
Running the command with -v 9 didn't change anything. The program still 
crashes after making an ssh connection to the backup server with no 
visual output, but doesn't return to the command prompt.
> What happens if you call `ssh ${BACKUP_USER}@${TARGETHOST}
> rdiff-backup.bat ${BACKUPTO}` like the cron job?
Same effect.
>   Or even something like
> `ssh ${BACKUP_USER}@${TARGETHOST} C:\Windows\System32\OpenSSH\ssh.exe
> [email protected] rdiff-backup --server`
This runs successfully, starting "rdiff-backup --server" on the backup 
server and closing when I kill the process on the backup server.
> But as you said that the issue appeared after an update of Windows, I
> can currently only imagine that something changed with SSH. I would look
> if perhaps something changed in the SSHD _and_ SSH configuration files
> between 1909 and 21H1, something which makes a difference between
> connecting interactively or not.
Unfortunately we have already upgraded all our Windows computers to 
21H1, so I don't have configuration files from 1909 to compare. For now 
I have worked around the problem by writing an expect script, run from 
the cron job on the backup server, that spawns an ssh connection and 
executes the batch file. This completes and exits successfully.
> On 01/11/2021 16:21, Michael Crider - HOEC wrote:
>> We have used rdiff-backup for well over 10 years for our Linux servers
>> and workstations, and until recently to back up Windows servers and
>> workstations we mounted their drives locally on the backup server and
>> ran rdiff-backup against the mount. When our first Windows 10
>> workstations arrived with v1909, we started having trouble reliably
>> mounting the drives, so we recently put the Windows executable of 2.0.5
>> on our Windows workstations and tried the same method we use for Linux -
>> a cron job on the backup server would ssh to the Windows workstation
>> (running the built-in OpenSSH server) and call a batch file that would
>> run rdiff-backup, sending the backup back to the server. Keys were in
>> place to allow passwordless connections. This way we could schedule
>> several workstations to run in sequence without having multiples overlap
>> in time (as might happen if we did the scheduling at the workstation).
>> That was very stable on workstations running Windows 10 1909 and below.
>> Then we upgraded all of our workstations to 21H1. Now we can manually
>> ssh to the Windows workstation and run the batch file and it runs just
>> fine. But if we run the cron job script that does the ssh and runs the
>> batch file, everything works (setting environment variables and updating
>> specific local files from network masters using scp) until the
>> rdiff-backup command. We don't have "echo off" on the batch file so we
>> can see the command issued. It makes the connection to the backup server
>> and starts rdiff-backup on it, but then it hangs and doesn't progress
>> any further, and no files are updated in the backup destination. We
>> started with rdiff-backup 2.05 using SysNative in the remote-schema,
>> then moved to 2.1.0a1-64 to see if that helped (changing the
>> remote-schema to System32 but leaving everything else the same). but
>> nothing changed except for an added warning about the server not
>> understanding the API. If we are running the cron script in a terminal
>> we can press Ctrl-C and exit. If it runs from a cron schedule we have to
>> kill rdiff-backup on either the workstation or the server. Has anyone
>> else seen something similar?
>>
>> The command in the cron job is: ssh ${BACKUP_USER}@${TARGETHOST}
>> rdiff-backup.bat ${BACKUPTO}; RDIFF_RESULT=$?
>>
>> The command in the batch file is:
>> C:\rdiff-backup-2.1.0a1-64\rdiff-backup.exe -v 6
>> --exclude-symbolic-links --remote-schema
>> "C:\Windows\System32\OpenSSH\ssh.exe %%s rdiff-backup --server"
>> --include "C:/FuturaData" --include "C:/Program Files (x86)/Futura
>> Systems/FuturaGIS/Staking Client" --exclude
>> "C:/Users/%BACKUP_USER%/AppData/Local/Temp" --exclude
>> "C:/Users/%BACKUP_USER%/AppData/Local/ESRI/Local Caches" --include
>> "C:/Users/%BACKUP_USER%" --exclude "C:/**" C:/
>> [email protected]::%BACKUPTO%
>>
>> Both use environment variables set on the command line of the script or
>> earlier in the script.