Recover FreeOTP Codes

First you have to instal adb and get it running on your smartphone.

$ adb shell

Afterwards issue the following command. Be aware that the output will be saved in the same folder:

adb backup -f freeotp-backup.ab -apk org.fedorahosted.freeotp

Use the Android Backup extractor to get decrypt the ab file:

abe.jar unpack freeotp-backup.ab freeotp-backup.tar

Unpack the .tar file and the only file you care about ist tokens.xml.

Use the following pyton script to get the tokens ( assuming tokens.xml is in the same folder as your python script):

#!/usr/bin/env python

import base64, json
import xml.etree.ElementTree as ET

verbose = False

root = ET.parse ('org.fedorahosted.freeotp/sp/tokens.xml').getroot()
for secrets in root.findall ('string'):
    name = secrets.get ('name')
    if name == 'tokenOrder':

    secret_json = secrets.text
    print ("secret name: {}".format(name))
    if verbose: print ("secret json: {}".format(secret_json))
    token = json.loads(secret_json);
    token_secret = token["secret"]
    if verbose: print("token secret: {}".format(token_secret))
    secret = bytes((x + 256) & 255 for x in token_secret)
    if verbose: print("token secret bytes {}".format(secret))
    code = base64.b32encode(secret)
    print("token secret base64: {}".format(code.decode()))

Headless Raspberry Pi

Step 1. Download a lite Raspbian image

Download the version you need. As we want to install a headless version download the Raspian XXXXX Lite version.

Step 2. Copy the image

From a Linux terminal use the following command to find your SD Card:

sudo fdisk -l

This will show you something like

Disk /dev/sdc 14.86 Gib ......

Ensure you select here the correct disk.

Afterwards copy the image with the following comand. Replace /dev/sdX by the correct path.

sudo dd bs=4M if=2019-07-10-raspbian-buster.img of=/dev/sdX conv=fsync

Step 3. Enable ssh

To activate ssh at the first start you just have to create a file ssh in the boot folder.

touch /run/media/your_username/boot/ssh

The path above might be different on your system.

Step 4. Add network info

Create a file in /run/media/your_username/boot/ called: wpa_supplicant.conf.

sudo nano /run/media/your_username/boot/wpa_supplicant.conf

Then paste the following into it (replace your country code, SSID and Password):

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev 
{ ssid="network SSID" 
  psk="network password" 

Step 5. Find your Raspberry Pi in your network

One solution is to login to your router.

In case you do not have access to your router you can scan your ip range with nmap. Use the following command and search for your Raspberry Pi:

sudo nmap -sP

Adjust to your ip range. In many cases it is or

Step 6. Login to your Raspberry Pi

Use the following command to login:

ssh pi@

Password by default: raspberry


ip route for wifi

In case you want to route the traffic of your linux machine of a specific IP through a specific interface ip routecommand should be used.

One example below asuming wlp2s0 is your wifi.

sudo ip route add via dev wlp2s0

This will lead all the traffic with target ip range trough the interface of your wifi (assuming is the wifi router).

I did not yet found a solution to route the traffic of a target “domain” through a specific interface. Happy for any input.


Pi-Backup automation

My Raspberry Pi has many little applications and it happend already 2 times that the microsd was not working anymore. Therefore I decided to automate a weekly backup for my NAS.

To get the job done. First you have to mount your NAS towards your Raspberry Pi.

  1. Make a mount towards the NAS
    Create the folder /mnt/backup
  2. Edit the the fstab file
    sudo nano /etc/fstab
  3. In my case it looks liket this
    // /mnt/backup cifs iocharset=utf8,uid=1001,gid=1001,x-systemd.automount,,vers=1.0,credentials=/home/user/.ds414-pi-backup.creds
  4. create a file for the credentials
    nano ~/.ds414-pi-backup.creds
    You might want to set chmod / chown permission to ensure nobody else can check your .creds file.
  5. It should look like this
  6. To make your changes in the fstab effect type
    sudo mount -a

Test your shared drive. You might want to re-start to check if the mount works fully automatically.

Once the shared drive is working download the following great script.
The script is fully based upon input from : The Raspberry Pi Backup Thread.

  1. Put the file in the desired location. I have it in /mnt/backup
  2. Make the script executable
    chmod +x /mnt/backup/
  3. Test the script. I run it with the following command
    sudo ./ start -L backup-$(date +%Y-%m-%d).log -czd /mnt/backup/$(uname -n)-$(date +%Y-%m-%d).img
  4. Create a file calling the with the correct variables
    nano /mnt/backup/
    The following content
    . /mnt/backup/ start -czdl /mnt/backup/$(uname -n)-$(date +%Y-%m-%d).img
    chmod +x /mnt/backup/
    This will create a backup file, gzip it and removing the unzipped version once finished. Furthermore, it will ad a log file into the folder. The PATH part has to be adjusted to your needs.

    Pay attention to change the PATH variable to your needs. You can find out more about your PATH by just typing env , or you use echo $PATH. Be aware that the cronjob is running with the user of the crontab. In this szenario I decided for root as the script needs multiple permissions only root has. 
    Therefore, the PATH has to be set correctly.
  5. Create a cronjob in order to automate the backup
    sudo crontab -e
  6. Add the following line at the end of the crontab file
    0 3 * * 1 /mnt/backup/
    This will create a cronjob running every week at 3 a.m

In order to test the script you can also change the cronjob to be executed each minute. Just type * * * * * instead of 0 3 * * * * within the crontab.

Usefull stuff:

In order to see the currently running cronjobs:

ps fauxww | grep -A 1 '[C]RON'

# Then use
Sudo kill PID

To see the furhter logging details: 

sudo tail /var/log/syslog

Restore of the Backup:

In order to restore the backup on a new sd card I just used the following program:

You just have to select “custom img” and select the previously unzipped gz file.