> I know the best mitigation for ransomware is to maintain off-site backups. I cannot do this. It is a design requirement not to have offline storage. The simp

> I know the best mitigation for ransomware is to maintain off-site backups. I cannot do this. It is a design requirement not to have offline storage. The simplest solution would be to maintain "off-site" backups... where "off-site" is actually right next to it (in the same room), but in a physically separate computer. Then you can use on it something like borgbackup's append-only mode (https://borgbackup.readthedocs.io/en/stable/usage/notes.html#append-only-mode-forbid-compaction https://borgbackup.readthedocs.io/en/stable/usage/notes.html...), so that ransomware running on other computers cannot overwrite old backups. Of course, this assumes that an attacker cannot access that computer other than through "borg serve" (it would be ideal if administration required physical console access to it), and that borgbackup doesn't have any bugs which allow bypassing the append-only restrictions in "borg serve". (This has a drawback, explained on that page, that a periodic prune/compact on the server to free space from old backups could allow an attacker to delete data from the repository; but it can be easily worked around by taking a filesystem snapshot of the repository before doing the prune/compact. In case the attacker corrupted the backups, you just have to find a snapshot from before the corruption.)