Excellent — and very important — question. Let’s evaluate your current setup and then identify resilience against ransomware, with practical hardening options you can apply right now.

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✅ Current Resilience Summary (Based on Your Setup)

Layer	Status
ZFS Snapshots	Yes — immutable, instant rollback point-in-time protection
Scheduled Backups	Yes — daily ZFS-based backups (possibly stored locally)
Offline Backups	Not yet — currently no mention of external/offsite isolation
VM Isolation	Yes — Windows Server is isolated in Proxmox VM
Access Model	Yes — RDP with CALs, admin via /admin, Proxmox console for fallback
Firewalling	Possibly — but not yet discussed; no mention of limiting RDP exposure
Restore Time (RTO)	Fast — VM restore or rollback in minutes
Recovery Point (RPO)	1 day — if nightly backups are in place

⚠️ Ransomware Weak Points (If Unaddressed)

1.	Backups on the same disk
•	Ransomware in the Windows VM may encrypt ZFS-mounted shares or mapped volumes, depending on permissions.
2.	No air-gapped/offsite backup
•	If backups are local-only (even snapshots), ransomware could destroy the Proxmox node or ZFS pool.
3.	Admin access misused
•	If a malicious actor gains RDP + admin access, they could destroy snapshots before encryption begins.
4.	No read-only snapshot access
•	Snapshots in ZFS can be deleted by a compromised root user unless protected.

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✅ Recommendations for True Ransomware Resilience

1. Keep ZFS Snapshots but Protect Them
   • Enable snapshot replication to a second disk or ZFS pool
   • Set readonly flags on snapshot datasets where possible
   
2. Create an Air-Gapped Backup
   

Method	How-To
External USB SSD (manual)	Plug in once/week, zfs send or Proxmox backup job, then unplug
NAS with pull-based rsync	Let NAS pull backups from Proxmox — keeps write access minimal
Cloud backup gateway	Use something like BorgBackup + Rclone for encrypted offsite copy

3. Harden RDP Access
   • Use Cloudflare Tunnel or VPN only
   • Never expose port 3389 to the internet directly
   • Use 2FA on admin accounts
   • Use mstsc /admin only for IT — not for daily use
   
4. Create Immutable Backups
   • Use Proxmox backup retention + write-once snapshots
   • If using rsync or zfs send, target read-only ZFS datasets
   
5. Test Restore Paths
   • Monthly test of snapshot rollback and backup restore
   • Keep documented steps for fast RTO (Recovery Time Objective)
   

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✅ If Implemented, Your Setup Will Offer:

Feature	Resilience Level
On-host ZFS snapshots	High
Immutable off-host backup	Very High
VM isolation via Proxmox	Strong
Hardened access (RDP + VPN)	Very Strong

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Would you like a resilience checklist in Markdown, including commands and policies for ZFS snapshot protection and backup hardening?