Windows-to-Linux Rsync Sync for Nextcloud (via SSH)

At a glance#

• Purpose: Replicate files from a Windows server to a Linux Nextcloud instance over SSH using rsync.
• Applies to: Windows Server with cwRsync or WSL, to Linux Nextcloud.
• Risk: Medium - misconfigured paths can overwrite data on the target.
• Time: About 1 hour.

Environment: - Windows Server 2012 - Ubuntu Linux (Nextcloud host) - Users: Real usernames (e.g., sam, harry, etc.)

Objective#

Sync specific user folders from a Windows Server to a Linux-based Nextcloud instance using rsync over SSH with key-based authentication.

Tools Used#

Windows Server Setup#

1. Install cwRsync#

1. Download: https://itefix.net/cwrsync
2. Install to:

C:\Program Files\cwRsync

1. Add to PATH:

System Properties → Environment Variables → Add:

C:\Program Files\cwRsync\bin

1. Test:

rsync --version

2. Install Win32-OpenSSH#

1. Download ZIP:

https://github.com/PowerShell/Win32-OpenSSH/releases

1. Extract to:

C:\Program Files\OpenSSH

1. Open PowerShell as Administrator:

cd 'C:\Program Files\OpenSSH'
powershell.exe -ExecutionPolicy Bypass -File install-sshd.ps1

1. Enable SSH:

Start-Service sshd
Set-Service sshd -StartupType Automatic

1. Allow SSH in firewall:

New-NetFirewallRule -Name sshd -DisplayName 'OpenSSH Server' -Enabled True -Direction Inbound -Protocol TCP -Action Allow -LocalPort 22

3. Create .ssh Folder and Authorized Key File#

1. On Windows:

mkdir "C:\Users\Administrator\.ssh"

1. On Linux:

ssh-keygen -t rsa -b 4096
cat ~/.ssh/id_rsa.pub

1. Paste public key into:

C:\Users\Administrator\.ssh\authorized_keys

1. Fix Permissions (PowerShell):

icacls "C:\Users\Administrator\.ssh" /inheritance:r /grant Administrator:F
icacls "C:\Users\Administrator\.ssh\authorized_keys" /inheritance:r /grant Administrator:F

4. Fix sshd_config#

File: C:\ProgramData\ssh\sshd_config

Do this:

• Uncomment or add:

`` PubkeyAuthentication yes AuthorizedKeysFile __PROGRAMDATA__/ssh/authorized_keys %h/.ssh/authorized_keys ``

• 💡 Optional: Comment out this block at last line to use .ssh folder:

`` # Match Group administrators # AuthorizedKeysFile __PROGRAMDATA__/ssh/administrators_authorized_keys ``

Restart SSH:

Restart-Service sshd

5. Test SSH from Linux#

ssh Administrator@<windows-ip>

✅ You should log in without password.

Folder Structure (Windows)#

Create folders for each user:

mkdir D:\sam\data
mkdir D:\harry\data
mkdir D:\kane\data

Add test files (optional):

D:\sam\data\report.pdf

Linux Side (Nextcloud Host)#

1. Folder Structure#

Ensure these exist:

/mnt/ncdata/sam/files/
/mnt/ncdata/harry/files/
/mnt/ncdata/kane/files/

Per-User Rsync Script#

Example: /root/sam.sh#

#!/bin/bash

REMOTE_USER="Administrator"
REMOTE_IP="198.51.100.251"
NEXTCLOUD_OCC="/var/www/nextcloud/occ"

USER="sam"
REMOTE_PATH="/cygdrive/d/${USER}/"
LOCAL_PATH="/mnt/ncdata/${USER}/files/"

echo "Syncing $USER ..."

rsync -avz --blocking-io -e ssh "${REMOTE_USER}@${REMOTE_IP}:${REMOTE_PATH}" "${LOCAL_PATH}"
chown -R www-data:www-data "/mnt/ncdata/${USER}"
sudo -u www-data php "${NEXTCLOUD_OCC}" files:scan --path="/${USER}/files/"

echo "Sync complete for $USER"

Repeat for each user:

• sam.sh
• harry.sh
• kane.sh

Schedule with Cron#

Edit crontab:

crontab -e

Add per-user jobs:

0 2 * * * /root/sam.sh >> /var/log/sync_sam.log 2>&1
5 2 * * * /root/harry.sh >> /var/log/sync_harry.log 2>&1
10 2 * * * /root/kane.sh >> /var/log/sync_kane.log 2>&1

Debugging Tips#

• SSH logs:

C:\ProgramData\ssh\logs\sshd.log or sshd-session.log

• Linux rsync test:

rsync -avz Administrator@<windows-ip>:/cygdrive/d/sam/ /mnt/ncdata/sam/files/

• Test permissions:

chown -R www-data:www-data /mnt/ncdata/sam

• Scan Nextcloud:

sudo -u www-data php /var/www/nextcloud/occ files:scan --path="/sam/files/"