Trace: • dsm7rescue

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Table of Contents

Rescue an encrypted volume

Prepare DSM to get access through SSH with password login enabled

  • Prepare 2 files within top level directory /volume2. The name is optional but must be a new directory so that these 2 files are kept intact when DSM get's updated, they must be treated as user files. In my setup Synology created /volume2 automatically when I created the fully encrypted /volume1.
  • File 1:
    #!/bin/sh
#
# This script checks availability of a fully encrypted volume1 and enables password authentication for SSH in case the volume is locked
# After restarting the SSH daemon it allows to login even though the homes directory is not accessible
# It requires script 'queryotp' to provide a valid google authenticator code without which it will do nothing
# Must be run as root, place it in the task scheduler with regular execution
# (c) Bernard Condrau
# 2026-08-31: initial
#
VOLUME="/volume1/homes"
SSHD_CONFIG="/etc/ssh/sshd_config"
PWD_AUTH_STR="PasswordAuthentication yes"
BASE_PATH=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
QUERY_OTP=$BASE_PATH"/queryotp"
LOG_FILE=$BASE_PATH"/../logs/enablepwd.log"
#
# check whether password authentication is enabled
head -n 1 $SSHD_CONFIG | grep -q "$PWD_AUTH_STR" && ENABLED="yes" || ENABLED=""
echo "$(date +'%Y-%m-%d %H.%M'): enablepwd task run" | tee -a $LOG_FILE
#
# check whether homes exists (e.g. volume1 is decrypted)
if [ -d "$VOLUME" ]; then
	echo "homes exists."
	if [[ -n "$ENABLED" ]]; then
		# disable password authentication
		$QUERY_OTP
		if [ $? -eq 0 ]; then
			sed -i "1d" $SSHD_CONFIG
			synosystemctl restart sshd
			echo "$(date +'%Y-%m-%d %H.%M'): \"$PWD_AUTH_STR\" removed" | tee -a $LOG_FILE
			exit 0
		fi
	fi
else
	echo "homes does not exist."
	if [[ -z "$ENABLED" ]]; then
		# enable password authentication
		$QUERY_OTP
		if [ $? -eq 0 ]; then
			sed -i "1i $PWD_AUTH_STR" $SSHD_CONFIG
			synosystemctl restart sshd
			echo "$(date +'%Y-%m-%d %H.%M'): \"$PWD_AUTH_STR\" added" | tee -a $LOG_FILE
			exit 0
		fi
	fi
fi
exit 1
  • File 2:
    #!/bin/sh
#
# Query OTP
#  must be run as root
# (c) Bernard Condrau
# 2026-08-31: initial
#
OTPQ="https://sec.condrau.com/html/synology.php?share=merkur-otp&auth=myaazrhHCTcNSekHcBp7qNEj"
AUTH=0;
CODE="`wget -qO - $OTPQ`"
SYNO=$(sudo synootp username=bco code=$CODE)
if [[ $SYNO == 'auth ok' ]]; then
	echo 'authenticated'
	exit 0
else
	sleep 35
	CODE="`wget -qO - $OTPQ`"
	SYNO=$(sudo synootp username=bco code=$CODE)
	if [[ $SYNO == 'auth ok' ]]; then
		echo 'authenticated'
		exit 0
	fi
fi
echo 'not authenticated'
exit 1

How to gain access to encrypted volumes when the KMIP Server was unavailable during DSM boot

  • If you can re-establish connection to the KMIP Server you can do the following:
    1. SSH into DSM
    2. if you want to continue using the KMIP Server:
      reboot
shutdown -r now
    3. if you do not want to continue using the KMIP Server:
      sudo /usr/syno/sbin/synoencvolume --auto-unlock-get-keys
    4. Log into DSM and open Storage Manager. You can now access DSM through it's web interface, but you cannot access your files.
    5. Reset the Encryption Key Vault in the Global Settings of the Storage Manager using the recovery key to disconnect your NAS from the KMIP Server.
    6. If your locked volume is not the same volume where your user home directories reside you can go to the Storage Manager and select the locked volume, then click the ellipsis (…) icon, and select Unlock. Upload your .rkey recovery file. The system will prompt you to enter a new vault password to recreate and repair the local key vault.

Recover an encrypted volume using an SSH shell

  • If you can not re-establish connection to the KMIP Server you can do the following:
    1. Identify the Target Device Node
      • Synology layers its storage using Linux mdadm (RAID) and Logical Volume Management (LVM). You need to find the logical volume path:
        sudo lvdisplay
      • Look for your volume path, e.g. LV Path /dev/vg1/volume_1
    2. Unlock the LUKS Container
      • Depending on what credentials you have, choose Option A or Option B
      • Option A: Using the Passphrase. Pass the LVM path to cryptsetup to open it. This will prompt you for the password:
        sudo cryptsetup luksOpen /dev/vg1/volume_1 mapped_volume
      • Option B: Using the Recovery Key (.rkey file). If you have the .rkey file saved on a USB drive or transferred via SSH to /tmp/volume1.rkey, use:
        sudo cryptsetup luksOpen /dev/vg1/volume_1 mapped_volume --key-file /tmp/volume1.rkey
      • Note: mapped_volume is just a temporary virtual name you assign for the next step.
    3. Mount the Filesystem
      • Synology volumes typically use the Btrfs or ext4 file systems. Create a temporary folder and mount the newly decrypted mapping:
        sudo mkdir -p /mnt/recovery
mount /dev/mapper/mapped_volume /mnt/recovery
    4. Access and Rescue Your Data
      • Your data is now fully unencrypted and accessible in plain text at /mnt/recovery. You can use command-line tools like cp, rsync, or tar to copy your files off to an external drive or another server.

How to Regenerate and Download a Recovery Key

  1. Open Storage Manager in Synology DSM
  2. Go to Storage and click on your encrypted volume
  3. Click the Settings button (or the three dots/action menu next to the volume)
  4. Locate the Recovery Key section
  5. Click Regenerate
  6. Enter your Vault Password when prompted to authorize the action
  7. The new recovery key file (.rkey) will download automatically to your computer's default download folder

Know How

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