rsync-backup-target

Configuration example
ssh API
- Adding new keys for backup
- Requesting a recover only key
  - as an admin
  - as a standard backup account
Troubleshooting

Usage of this service

Configuration example

rsync-backup-target:
  # docker-compose:
  #   ports:
  #     - "10023:22"
  options:
    admin:   ## These keys are for the allowed rsync-backup to write stuff with rsync
      myadmin:
      - "ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDESdz8bWtVcDQJ68IE/KpuZM9tAq\
        ZDXGbvEVnTg16/yWqBGQg0QZdDjISsPn7D3Zr64g2qgD9n7EZghfGP9TkitvfrBYx8p\
        7JkkUyt8nxklwOlKZFD5b3PF2bHloSsmjnP8ZMp5Ar7E+tn1guGrCrTcFIebpVGR3qF\
        hRN9AlWNR+ekWo88ZlLJIrqD26jbWRJZm4nPCgqwhJwfHE3aVwfWGOqjSp4ij+jr2ac\
        Arg7eD4clBPYIqKlqbfNRD5MFAH9sbB6jkebQCAUwNRwV7pKwCEt79HnCMoMjnZh6Ww\
        6TlHIFw936C2ZiTBuofMx7yoAeqpifyzz/T5wsFLYWwSnX rsync@zen"

ssh API

Adding new keys for backup

This can be done through the admin accounts configured in compose.yml.

You can use then ssh myadmin@$RSYNC_BACKUP_TARGET ssh-key:

$ ssh myadmin@$RSYNC_BACKUP_TARGET ssh-key ls
$ ssh myadmin@$RSYNC_BACKUP_TARGET ssh-key add "ssh-rsa AAA...Jdhwhv rsync@sourcelabel"
$ ssh myadmin@$RSYNC_BACKUP_TARGET ssh-key ls
..Jdhwhv sourcelabel
$ ssh myadmin@$RSYNC_BACKUP_TARGET ssh-key rm sourcelabel
$ ssh myadmin@$RSYNC_BACKUP_TARGET ssh-key ls
$

Requesting a recover only key

as an admin

As an admin, by requesting a recover-only key on an ident that you own, you are allowed to read (and only read) the content of the given ident. This will allow you to give the credentials to any new host to have a direct read access so-as to deploy the backup on a new host.

$ ssh myadmin@$RSYNC_BACKUP_TARGET ssh-key request-recovery-key myident > /tmp/private_key
$ chmod 500 /tmp/private_key
$ rsync -e "ssh -p 22 -i /tmp/private_key -l rsync" \
      -azvArH --delete --delete-excluded \
      --partial --partial-dir .rsync-partial \
      --numeric-ids $RSYNC_BACKUP_TARGET:/var/mirror/myident/etc/ /tmp/etc

This key will expire after 15 mn of the last recovery.

as a standard backup account

With a standard backup account, you can log on as rsync user and request without any arguments a recovery key. Indeed, every standard backup account is tied to one backup identifier only. So the recover key received will be for this backup identifier only.

You'll probably want to use the received key from another computer to restore the backup for instance.

$ ssh rsync@$RSYNC_BACKUP_TARGET request-recovery-key > /tmp/private_key
$ chmod 500 /tmp/private_key
$ rsync -e "ssh -p 22 -i /tmp/private_key -l rsync" \
      -azvArH --delete --delete-excluded \
      --partial --partial-dir .rsync-partial \
      --numeric-ids $RSYNC_BACKUP_TARGET:/var/mirror/myident/etc/ /tmp/etc

Troubleshooting

Faking access from client

This should work:

RSYNC_BACKUP_TARGET_IP=172.18.0.2
rsync -azvA -e "ssh -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no" \
  /tmp/toto "$RSYNC_BACKUP_TARGET":/var/mirror/client1

Direct ssh access should be refused

RSYNC_BACKUP_TARGET_IP=172.18.0.2
ssh -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no \
  "$RSYNC_BACKUP_TARGET"

Wrong directory should be refused

RSYNC_BACKUP_TARGET_IP=172.18.0.2
rsync -azvA -e "ssh -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no" \
  /tmp/toto "$RSYNC_BACKUP_TARGET":/var/mirror/client2

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