Horror Stories from Digiland

On May 2019 we did a presentation at University of Nicosia about digital rights and horror stories regarding their violations. We talked about ways of how technology can be used against us, and about actions and tools we can use to protect ourselves.

You can find the presentation material here:

Horror Stories from Digiland

Here you can find some references that help in the creation of the presentation. This is a shorter version of an earlier presentation I did in greek so the references may not match exactly to this one.



Sony Rootkit

Lower Merion High School

Afgan War Logs


The Fappening

No cloud

Ashley Maddison

VW Scandal

Vault 7


Tesla Cars

Mobile Telephony


Smart TVs





Cabridge Analytica


Backdoors – Malware

HTTPS Interception

Brain decoding – fMRI

Political Nightmares

Net Neutrality

So why should I care?

Protect yourself

Alternative social media

Protections in Telephony

Protection in Email

Other Solutions


Digital Rights Organizations

Rysiek\’s Law

Digital Rights in Cyprus

Digital Rights

Orwell vs Huxley

General Linux

Installing a software RAID 10 Debian system with LUKS disk encryption

In this guide we will be installing Debian 9 (aka stretch) on a physical server with 4 disks. The role of this machice is to be used as a Storage/NAS system. We will create a software RAID 10 setup, with LVM and LUKS full disk encryption. Our goals:

  • Install a Debian 9 with RAID10/LVM/LUKS.
  • Secure SSH.
  • Enable Firewall (UFW).
  • Setup bonding with the two network cards.
  • Setup remote system unlock with dropbear and initramfs.
  • Setup disk-monitoring with smartmontools and mdadm.
  • Setup kexec for faster reboots.

Computer specs

  • Type: HP ProLiant MicroServer
  • CPU: AMD Turion(tm) II Neo N40L Dual-Core Processor
  • RAM: 2GB
  • Disks: 4x3TB SATA
  • Network:
    • Broadcom Limited NetXtreme BCM5723 Gigabit Ethernet PCIe (on board)
    • Intel Corporation 82574L Gigabit Network Connection (extra)


  • Server IP:
  • Netmask:
  • Gateway IP:
  • DNS IP:
  • Hostname:

Install Debian stretch

Basic Settings

It would probably be more clear if there were screenshots for each step, but this was an installation on a physical server and taking photos for each step, opposes my laziness :). Just follow the instructions and you will be fine.

  • Choose: Install
  • Language: English
  • Country: other
  • Europe: Cyprus
  • Country to base default locale settings: United States
  • Keymap to use: American English
  • Primary network interface: enp3s0: Broadcom Limeted NetXtream BCM5723 Gigabit Ethernet PCIe
  • Let it get an IP from DHCP
  • Hostname: storage
  • Domain name:
  • Root password: SomethingBigAndUnpredictable
  • Re-enter password to verify: SomethingBigAndUnpredictable
  • Full name: Sysadmin
  • Username: admin
  • Choose a password for the new user: AlsoSomethingBigAndUnpredictable
  • Re-enter password to verify: AlsoSomethingBigAndUnpredictable
  • Select your time zone: Asia/Nicosia
  • Partitioning method: Manual

Feel free to adjust the above according to your own preferences.


There are 4 disks of 3TB each (3.0 TB SATA):

  • SCSI1 (0,0,0) (sda)
  • SCSI2 (0,0,0) (sdb)
  • SCSI3 (0,0,0) (sdc)
  • SCSI4 (0,0,0) (sdd)

Not really SCSI but SATA in fact.

Partition the devices

Then create a raid partition for /boot:

  • Select the free space of sda and ‘Enter’
  • Create a new partition
  • New partition size: 512 MB
  • Location of new partition: Beginning
  • Use as: physical volume for RAID
  • Done setting up the partition

Lastly create the raid partition to be used by the encrypted volume:

  • Select the free space of sda and ‘Enter’
  • Create a new partition
  • New partition size: 3.0 TB
  • Location of new partition: Beginning
  • Use as: physical volume for RAID
  • Done setting up the partition

Repeat the above steps for sdb, sdc and sdd.

Setup Software RAID 10

First select ‘Configure software RAID’ and follow these steps:

  • Write the changes to the storage devices and configure RAID? Yes

The we create the software RAID (MD) devices. First we create device md0 for /boot:

  • Create MD Device
  • RAID10
  • Number of active devices inn the RAID10 array: 4
  • Number of spare devices inn the RAID10 array: 0
  • Active devices for the RAID10 array (use ‘Space bar’ to select)
    • /dev/sda2
    • /dev/sdb2
    • /dev/sdc2
    • /dev/sdd2
  • Press ‘Continue’ when done.

Then we create the software RAID device to be used for the encrypted volume (md1):

  • Create MD Device
  • RAID10
  • Number of active devices inn the RAID10 array: 4
  • Number of spare devices inn the RAID10 array: 0
  • Active devices for the RAID10 array (use the ‘Space bar’ to select)
    • /dev/sda3
    • /dev/sdb3
    • /dev/sdc3
    • /dev/sdd3
  • Press ‘Continue’ when done.
  • Press ‘Finish’ when done.

Create the /boot volume

When done press ‘Finish partitioning and write changes to disk’.`

When finished you will see a ‘RAID10 device #0 1GB Software RAID device’:

  • Select: #1 1.0GB
  • Use as: Ext4 journaling file system
  • Mount point: /boot
  • Done setting up the partition

Setup the encrypted volume

We will be using the software RAID /dev/md1 device for the encrypted volume.

Now select ‘Configure encrypted volumes’ and follow these steps:

  • Write the changes to disk and configure encrypted volumes? Yes
  • Create encrypted volumes

  • Select: /dev/md1
  • Erase data: yes (this will take a long time)
  • Done setting up the partition

  • Write the changes to disk and configure encrypted volumes? Yes

  • Finish
  • Encryption passphrase: MyVeryLongEncryptionPassphrase
  • Re-enter the passphrase to verify: MyVeryLongEncryptionPassphrase
  • Setup LVM

    Next we select the ‘Configure the Logical Volume Manager’ option and follow these steps:

    • Write the changes to disks and configure LVM? Yes
  • Create volume group

  • Volume group name: VG00
  • Devices for the new volume group:
    • /dev/mapper/md1_crypt
  • Then we create the Logical Volumes (LV). First let’s create a SWAP volume:

    • Create logical volume
    • Volume group: VG00
    • Logical volume name: SWAP
    • Logical volume size: 2048MB (2G is more than enough for this system)

    Lastly we create the system (ROOT) volume. On an enterprise installation we may want to use different volumes for /usr, /home, /var, etc but for a home installation we will be fine to use just one.

    • Create logical volume
    • Volume group: VG00
    • Logical volume name: ROOT
    • Logical volume size: 5996818MB (All available space)

    Press ‘Finish’ when done.

    Start the installation

    After all the steps are completed these Logical Volumes will be present on the system:

    • LVM VG VG00, LV ROOT 0 6.0 TB
    • LVM VG VG00, LV SWAP 0 2.0 GB

    Create the ROOT filesystem

    Under the ‘LVM VG VG00, LV ROOT 0 6.0 TB’ line select the ‘#1 6.0TB’ option:

    • Use as: Ext4 journaling file system
    • Mount point: /
    • Done setting up this partition

    Create the SWAP space

    Under the ‘LVM VG VG00, LV SWAP 0 2.0 GB’ line select the ‘#1 2.0GB’ option:

    • Use as: swap area
    • Done setting up this partition

    Now we are ready to write the changes and start the installation. Press the ‘Finish partitioning and write changes to disk’ option to continue:

    • Write the changes to disks? Yes

    Wait for the base install to finish. Then select a country close to you. No debian mirrors in Cyprus so I use UK:

    • Debian archive mirror country: United Kingdom
    • Debian archive mirror:
    • HTTP proxy: (none)

    Wait for the APT configuration to Finish.

    • Participate in the package usage survey: no
  • Choose software to install:

    • SSH server
    • standard system utilities
  • Wait while software is installing

    • Install the GRUB boot loader to the master boot record.
    • Device for boot loader installation:
      • /dev/sda

    Wait for the installation to finish and reboot. Remember to remove the USB during the reboot cycle.

    Post install steps

    During start-up you will see the ‘Please unlock md1_crypt’ prompt. Type your LUKS passphrase to unlock the disk and continue.

    Update and Upgrade

    Login as root:

    # apt update && apt -y dist-upgrade

    Install essential packages

    # apt -y install vim htop multitail ntp byobu ufw unattended-upgrades downtimed

    Secure ssh

    You need to generate an SSH key pair on you PC, if you don’t have one (you should!):

    $ ssh-keygen -b 4096

    Copy the public key:

    $ cat ~/.ssh/

    Paste the public key at the end of the /root/.ssh/authorized_keys file in your server and try to login from your PC:

    $ ssh root@

    Some final adjustments on your SSH config (/etc/ssh/sshd_config). Change these values:

    Port 2233
    PasswordAuthentication no

    Restart SSH:

    # systemctl restart ssh.service

    Enable the UFW firewall

    We are using port 2233 for SSH so we need to allow that and enable the firewall:

    # ufw allow 2233/tcp
    # ufw enable

    Setup bonding

    Since we have two ethernet cards, we may take advantage of thr Linux bonding feature and join them as one. We will be using the Adaptive load balancing mode which provides load balancing of transmit, load balancing of receive for IPv4 and requires no configuration from the switch side.

    First we need to install ifenslave:

    # apt -y install ifenslave

    Set up this in /etc/network/interfaces:

    # This file describes the network interfaces available on your system
    # and how to activate them. For more information, see interfaces(5).
    source /etc/network/interfaces.d/*
    # The loopback network interface
    auto lo
    iface lo inet loopback
    # enp2s0 is manually configured, and slave to the "bond0" bonded NIC
    auto enp2s0
    iface eth0 inet manual
        bond-master bond0
    # enp3s01 is also manually configured, thus creating a 2-link bond.
    auto enp3s0
    iface eth1 inet manual
        bond-master bond0
    # bond0 is the bonded NIC and can be used like any other normal NIC.
    # bond0 is configured using static network information.
    auto bond0
    iface bond0 inet static
        # bond0 uses adaptive load balancing
        bond-mode 6
        bond-miimon 100
        bond-slaves enp2s0 enp3s0

    An ifup bond0 should bring the bonded interface up. Or you can just reboot.

    Setup remote-unlock with dropbear

    The server will be a headless system, located in a difficult to access location. So we need a way to unlock it when a power failure occurs. The most convenient way to do this is to use a mandos server but convenience comes at a cost. A safer and easier way is to use dropbear during boot (initrd). The weak point of this solution is that the server will be basically offline until the sysadmin manually unlocks it, to boot.

    First we install dropbear for initrd:

    # apt -y install dropbear-initramfs

    Then we set a custom ssh port for dropbear. This better be different than the custom ssh port we used earlier. Change the dropbear port to 2244 in /etc/dropbear-initramfs/config:

    DROPBEAR_OPTIONS="-p 2244"

    Add the static IP in the initramtools configuration (/etc/initramfs-tools/initramfs.conf):


    Copy the authorized_keys file in /etc/dropbear-initramfs:

    # cp /root/.ssh/authorized_keys /etc/dropbear-initramfs/

    Regenerate the initrd file:

    # update-initramfs -u

    Now reboot and ssh to it to test it:

    $ ssh -p 2244 root@

    If your pubkeys are in place you will enter a busybox shell. Enter the crypt-unlock command, supply your unlock passphrase and the system will boot to the encrypted system.

    Setup a local MTA for notifications

    We will be using our main mailserver as a smarthost for mail to go through.

    Install the postfix MTA and the mail utility:

    # apt -y install postfix mailutils

    Answer these questions:

    • General type of mail configuration: Internet with smarthost
    • System mail name:
    • SMTP relay host (blank for none):

    Test it:

    # echo 'Testing #1' | mail -s 'Test #1'

    If you get a mail in your mailbox then everything is set. If not extra configuration may be needed on the smarthost. Contact the sysadmin of the smarthost, or check the logs if you access to it.

    Setup pro-active disk monitoring

    Install smartmontools:

    # apt -y install smartmontools

    Enable S.M.A.R.T, offline testing, attribute autosave, short and long test on all 4 devices. Add these lines in /etc/smartd.conf:

    /dev/sda -a -d sat -o on -S on -s (S/../.././02|L/../../6/03) -m -M exec /usr/share/smartmontools/smartd-runner
    /dev/sdb -a -d sat -o on -S on -s (S/../.././02|L/../../6/03) -m -M exec /usr/share/smartmontools/smartd-runner
    /dev/sdc -a -d sat -o on -S on -s (S/../.././02|L/../../6/03) -m -M exec /usr/share/smartmontools/smartd-runner
    /dev/sdd -a -d sat -o on -S on -s (S/../.././02|L/../../6/03) -m -M exec /usr/share/smartmontools/smartd-runner

    Restart smartmontools:

    # systemctl restart smartmontools.service

    Setup Software RAID10 monitoring

    We also need to setup monitoring for the software raid. Add your email address in the /etc/mdadm/mdadm.conf file:


    Restart the mdmonitor service:

    # systemctl restart mdmonitor.service

    Setup kexec for faster reboots

    Kexec is a Linux kernel mechanism that can load a fresh kernel from a running system. This results in a “reboot” without in fact rebooting the computer. The system loads a new kernel, the system appears “rebooted” but skipping the BIOS?UEFI initialization, thus resulting in faster reboots.

    Install kexec-tools:

    # apt -y install kexec-tools

    The ‘Should kexec-tools handle reboots (sysvinit only)?’ question is related only to sysvinit systems. Since we are using systemd, it has no effect in our case.

    Now if you want to reboot instead of running reboot you can run systemctl kexec. The latter command will reboot the system without going though BIOS/UEFI, POST etc and your system downtime is minimized.

    And we are done! Store your server in a protected location, add a UPS for power backup and you are ready.



    Installing Ceph using ceph-deploy

    Ceph is a distributed open source storage solution that supports Object Storage, Block Storage and File Storage.

    Other open source distributed storage systems are GlusterFS and HDFS.

    In this guide, we describe how to setup a basic Ceph Cluster for Block Storage. We have 25 nodes on our setup. The masternode is a MASS Region and Rack controller. The rest of the nodes are Ubuntu 16.04 deployed through MAAS. The recommended filesystem for Ceph is XFS and this is what is used on the nodes.

    This guide is based on the Quick Installation guide from the Ceph Documentation. This guide uses the ceph-deploy tool which is a relatively quick way to setup Ceph, especially for newbies. There is also the Manual Installation, deployment through Ansible and juju.



    • 1 deploy node (masternode). MAAS region and rack controler is installed plus Ansible
    • 3 monitor nodes (node01,node11,node24). Ubuntu 16.04 on XFS deployed through MAAS
    • 20 OSD nodes (node02-10,12-23).

    Create an Ubuntu user on masternode

    It would be of convenience to create an ubuntu user on the masternode. with passwordless sudo access:

    $ sudo useradd -m -s /bin/bash ubuntu

    Run visudo and give passwordless sudo access to the ubuntu user:

    ubuntu  ALL=NOPASSWD:ALL

    Generate an SSH key pair for the ubuntu user:

    $ ssh-keygen -b 4096
    Generating public/private rsa key pair.
    Enter file in which to save the key (/home/ubuntu/.ssh/id_rsa): 
    Enter passphrase (empty for no passphrase): 
    Enter same passphrase again: 
    Your identification has been saved in /home/ubuntu/.ssh/id_rsa.
    Your public key has been saved in /home/ubuntu/.ssh/
    The key fingerprint is:
    SHA256:t1zWURVk7j6wJPkA3VmbcHtAKh3EB0kyanORVbiiBkU ubuntu@masternode
    The key's randomart image is:
    +---[RSA 4096]----+
    |       .E +**B=*=|
    |        ..o==oOo+|
    |       .+.o.o=.=.|
    |      .. oo.o....|
    |       .S..=oo.. |
    |        oo += +  |
    |       .  o  o o |
    |                .|
    |                 |

    Deploy the /home/ubuntu/.ssh/ pubkey on all the nodes (append in /home/ubuntu/.ssh/authorized_keys). You could add this pubkey on the MAAS user before deploying Ubuntu 16.04 on the nodes.

    Set /etc/hosts

    $ for ID in {01..24}; do echo "$(dig +short node${ID}.maas @ node${ID}.maas node${ID}"; done > nodes.txt

    It should look like this: node01.maas node01 node02.maas node02 node03.maas node03 node04.maas node04 node05.maas node05 node06.maas node06 node07.maas node07 node08.maas node08 node09.maas node09 node10.maas node10 node11.maas node11 node12.maas node12 node13.maas node13 node14.maas node14 node16.maas node16 node17.maas node17 node18.maas node18 node19.maas node19 node20.maas node20 node21.maas node21 node22.maas node22 node23.maas node23 node24.maas node24

    Now you can append the result in /etc/hosts:

    $ cat nodes.txt | sudo tee -a /etc/hosts

    Ansible setup

    Use this setup in /etc/ansible/hosts on masternode:


    Install python on all the nodes

    $ for ID in {01..24}
    > do
    >  ssh node${ID} "sudo apt -y install python-minimal"
    > done

    Ensure time synchronization of the nodes

    Install the theodotos/debian-ntp role from Ansible Galaxy:

    $ sudo ansible-galaxy install theodotos.debian-ntp

    Create a basic playbook ntp-init.yml:

    - hosts: nodes
      remote_user: ubuntu
      become: yes
         - { role: theodotos.debian-ntp, ntp.server: masternode }

    Apply the playbook:

    $ ansible-playbook ntp-init.yml

    Verify that the monitor nodes are time synchronized:

    $ ansible ceph-mon -a 'timedatectl'
    node11 | SUCCESS | rc=0 >>
          Local time: Fri 2017-04-28 08:06:30 UTC
      Universal time: Fri 2017-04-28 08:06:30 UTC
            RTC time: Fri 2017-04-28 08:06:30
           Time zone: Etc/UTC (UTC, +0000)
     Network time on: yes
    NTP synchronized: yes
     RTC in local TZ: no
    node24 | SUCCESS | rc=0 >>
          Local time: Fri 2017-04-28 08:06:30 UTC
      Universal time: Fri 2017-04-28 08:06:30 UTC
            RTC time: Fri 2017-04-28 08:06:30
           Time zone: Etc/UTC (UTC, +0000)
     Network time on: yes
    NTP synchronized: yes
     RTC in local TZ: no
    node01 | SUCCESS | rc=0 >>
          Local time: Fri 2017-04-28 08:06:30 UTC
      Universal time: Fri 2017-04-28 08:06:30 UTC
            RTC time: Fri 2017-04-28 08:06:30
           Time zone: Etc/UTC (UTC, +0000)
     Network time on: yes
    NTP synchronized: yes
     RTC in local TZ: no

    Check also the OSD nodes:

    $ ansible ceph-osd -a 'timedatectl'

    Install Ceph

    Install ceph-deploy

    On masternode:

    $ sudo apt install ceph-deploy

    Create a new cluster and set the monitor nodes (must be odd numbered):

    $ ceph-deploy new node01 node11 node24

    Install ceph on master node and all other nodes:

    $ ceph-deploy install masternode node{01..24}

    Deploy the monitors and gather the keys:

    $ ceph-deploy mon create-initial

    Prepare the OSD nodes

    Create the OSD directories

    Create the OSD directories on the OSD nodes:

    $ I=0;
    $ for ID in {02..10} {12..14} {16..23}
    > do 
    >  ssh -l ubuntu node${ID} "sudo mkdir /var/local/osd${I}"
    >  I=$((${I}+1))
    > done;

    Verify that the OSD directories are created:

    $ ansible ceph-osd -a "ls /var/local" | cut -d\| -f1 | xargs -n2 | sort
    node02 osd0
    node03 osd1
    node04 osd2
    node05 osd3
    node06 osd4
    node07 osd5
    node08 osd6
    node09 osd7
    node10 osd8
    node12 osd9
    node13 osd10
    node14 osd11
    node16 osd12
    node17 osd13
    node18 osd14
    node19 osd15
    node20 osd16
    node21 osd17
    node22 osd18
    node23 osd19

    Nodes 01, 11 and 24 are excluded because those are the monitor nodes.

    Fix OSD permissions

    Because of some bug we need to change the OSD directories owneship to ceph:ceph. Otherwise you will get this:

    ** ERROR: error creating empty object store in /var/local/osd0: (13) Permission denied

    Change the ownership of the OSD directories on the OSD nodes:

    $ I=0;
    $ for ID in {02..10} {12..14} {16..23}
    > do 
    >   ssh -l ubuntu node${ID} "sudo chown ceph:ceph /var/local/osd${I}"
    >   I=$((${I}+1))
    > done;

    Prepare the OSDs

    $ I=0
    $ for ID in {02..10} {12..14} {16..23}
    > do
    >   ceph-deploy --username ubuntu osd prepare node${ID}:/var/local/osd${I}
    >   I=$((${I}+1))
    > done

    Activate the OSDs

    For nodes 02 – 10:

    $ I=0
    > for ID in {02..10} {12..14} {16..23}
    > do
    >   ceph-deploy --username ubuntu osd activate node${ID}:/var/local/osd${I}
    >   I=$((${I}+1))
    > done

    Deploy the configuration file and admin key

    Now we need to deploy the configuration file and admin key to the admin node and our Ceph nodes. This will save us from having to specify the monitor address and keyring every time we execute a Ceph cli command.

    $ ceph-deploy admin masternode node{01..24}

    Set the keyring to be world readable:

    $ sudo chmod +r /etc/ceph/ceph.client.admin.keyring

    Test and verify

    $ ceph health
    HEALTH_WARN too few PGs per OSD (9 < min 30)
    HEALTH_ERR clock skew detected on mon.node11, mon.node24; 64 pgs are stuck inactive for more than 300 seconds; 64 pgs stuck inactive; 64 pgs stuck unclean; Monitor clock skew detected 

    Out newly build cluster is not healthy. We need to increase Placement Groups. The formula is the number_of_minimum_expected_PGs (30) times the number_of_OSDs (20) and rounded to the closest power of 2:

    30x20=500 => pg_num=512

    Increase PGs:

    $ ceph osd pool set rbd pg_num 512

    Now we run ceph health again:

    $ ceph health
    HEALTH_WARN pool rbd pg_num 512 > pgp_num 64

    Still some tweaking needs to be done. We need to adjust pgp_num to 512:

    $ ceph osd pool set rbd pgp_num 512

    And we are there at last:

    $ ceph health

    Create a Ceph Block Device device

    Check the available storage:

    $ ceph df
        SIZE       AVAIL      RAW USED     %RAW USED 
        11151G     10858G         293G          2.63 
        NAME     ID     USED     %USED     MAX AVAIL     OBJECTS 
        rbd      0       306         0         3619G           4 

    Now we need to create a RADOS Block Device (RBD) to hold our data.

    $ rbd create clusterdata --size 4T --image-feature layering

    Check the new block device:

    $ rbd ls -l
    clusterdata 4096G          2

    Map the block device:

    $ sudo rbd map clusterdata --name client.admin

    Format the clusterdata device:

    $ sudo mkfs -t ext4 /dev/rbd0

    Mount the blobk device:

    $ mkdir /srv/clusterdata
    $ mount /dev/rbd0 /srv/clusterdata

    Now we have a block device for data that is distributed among the 21 storage nodes.

    Here’s is a summary of some useful monitoring and troubleshooting commands for ceph

    $ ceph health
    $ ceph health detail
    $ ceph status (ceph -s)
    $ ceph osd stat
    $ ceph osd tree
    $ ceph mon dump
    $ ceph mon stat
    $ ceph -w
    $ ceph quorum_status --format json-pretty
    $ ceph mon_status --format json-pretty
    $ ceph df

    If you run into trouble contact the awesome folks at the #ceph IRC channel, hosted on Open and Free Technology Community IRC network.

    Start over

    In case you messed up the procedure and you need to start over you can use the following commands:

    $ ceph-deploy purge masternode node{01..24}
    $ ceph-deploy purgedata masternode node{01..24}
    $ ceph-deploy forgetkeys
    $ for ID in {02..11} {11..23}; do ssh node${ID} "sudo rm -fr /var/local/osd*"; done
    $ rm ceph.conf ceph-deploy-ceph.log .cephdeploy.conf

    NOTE: this procedure will destroy your Ceph cluster along with all the data!


    Using ceph-deploy maybe an easy way to get started with Ceph, but it does not provide much customization. For a more fine tuned setup you maybe better with the Manual Installation, even though there is a steeper learning curve.



    Installing Wiki.js on Ubuntu 16.04

    Wiki.js is an elegant looking wiki based on Markdown. It supports LDAP and many more authentication mechanisms. In this guide we describe how to install Wiki.js on Ubuntu 16.04.


    • An Ubuntu 16.04 instance.

    Install curl, Node.js v8.x and build-essential:

    # apt -y install curl
    # curl -sL | bash -
    # apt -y install nodejs build-essential

    Install MongoDB v3.4

    # apt-key adv --keyserver hkp:// --recv 0C49F3730359A14518585931BC711F9BA15703C6
    # echo "deb [ arch=amd64,arm64 ] xenial/mongodb-org/3.4 multiverse" | tee /etc/apt/sources.list.d/mongodb-org-3.4.list
    # apt update
    # apt -y install mongodb-org

    Start MongoDB:

    # systemctl start mongodb

    Enable MongoDB at startup:

    # systemctl enable mongodb

    Install git

    The version that comes with Ubuntu 16.04 fills the minimum requirements so there is no need to install it from upstream.

    # apt -y install git

    Install Wiki.js

    # mkdir /srv/wiki.js
    # cd /srv/wiki.js
    # npm install wiki.js@latest

    You will get this message:

    > Browse to http://your-server:3000/ to configure your wiki! (Replaced your-server with the hostname or IP of your server!)
    ▐   ⠂    ▌ I'll wait until you're done ;)

    Do as the message says. Let the wizard wait until we are done, and open another shell to work with.

    Setup nginx

    Install Nginx:

    # apt -y install nginx

    Create this VirtualHost configuration (/etc/nginx/sites-available/

    server {
        listen      [::]:80 ipv6only=off;
        return      301 https://$server_name$request_uri;
    server {
        listen 443 ssl http2;
        listen [::]:443 ssl http2;
        ssl_session_timeout 1d;
        ssl_session_cache shared:SSL:50m;
        ssl_session_tickets off;
        ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
        ssl_prefer_server_ciphers on;
        ssl_certificate /etc/nginx/ssl/;
        ssl_certificate_key /etc/nginx/ssl/;
        ssl_trusted_certificate /etc/nginx/ssl/CA.crt;
        location / {
            proxy_set_header Host $http_host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_http_version 1.1;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection "upgrade";
            proxy_next_upstream error timeout http_502 http_503 http_504;

    Enable the VirtualHost:

    # cd /etc/nginx/sites-enabled/
    # ln -s ../sites-available/
    # unlink default

    Restart Nginx:

    # systemctl restart nginx

    Configure Wiki.js

    After the installation you will be asked if you wish to run the configuration wizard. Select this and continue:

    Yes, run configuration wizard on port 3000 (recommended)

    Now browse to and follow the installation wizard:

    • Welcome!: Start
    • System Check (if all good): Continue
    • General:
      • Site title: ExampleWiki
      • Host:
      • Port: 3000
      • Site UI Language: English
      • Public Access: Not selected
      • Press: Continue
    • Important Considerations: Continue
    • Database: mongodb://localhost:27017/wiki
    • Database Check: Continue:
    • Paths:
      • Local Data Path: ./data
      • Local Repository Path: ./repo
    • Git Repository: Skip this step
    • Git Repository Check: Continue
    • Administrator Account
      • Administrator Email:
      • Password: MySecretCombination
      • ConfirmPassword: MySecretCombination
    • Finalizing: Start

    Enable Wiki.js on startup

    # npm install -g pm2
    # pm2 startup
    # pm2 save

    Setup LDAP

    This is an optional step for those wishing to integrate Wiki.js in their LDAP infrastructure.


    Connect to the LDAP (AD) server and get all certificates:

    openssl s_client -showcerts -connect | tee ldap.log

    Hit ‘Ctrl-C’ to end the command.

    The certificate with the ID ‘1’ in ldap.log is the ISSUING CA certificate. Extract the CUT IST ISSUING CA certificate and save it in cut_issuing_ca.crt:

    -----END CERTIFICATE-----

    Verify the certificate with:

    openssl x509 -text -in cut_issuing_ca.crt

    Add the CUT ISSUING CA in the trusted chain of the system:

    cp cut_issuing_ca.crt /usr/local/share/ca-certificates/

    Configure LDAP for Wiki.js

    Make these changes in /srv/wiki.js/config.yml:

        enabled: true
        url: 'ldap://'
        bindDn: 'cn=wiki,ou=dsa,dc=example,dc=com'
        bindCredentials: 'MyLDAPCredentials'
        searchBase: 'ou=people,dc=example,dc=com'
        searchFilter: '(uid={{username}})'
        tlsEnabled: true
        tlsCertPath: '/etc/ssl/certs/ca-certificates.crt'

    Give Access permissions to authenticated users

    Visit the Admin URL:

    Click on ‘Users’. You will get a list of users. You can give ‘Read and Write’ access to them from the ‘Access Rights’ field and you can upgrade them to ‘Global Administrators’ from the ‘Role Override’ field.

    NOTE: For LDAP the users need to login first before they are allowed to write.

    Enjoy your newly created Wiki!



    Setting up a Dual NIC, LXD Container

    LXD is a relatively new technology by Canonical. It is a container hypervisor that builds on top of LXC. It shares some similarities with Docker, but LXD focuses on full blown containerized systems, instead of containerized applications.

    LXD/LXC creates lighter systems than VM hypervisors, and it is an easy way to experiment with different software without messing up with your system. You can also use it in production, to run Linux systems with much greater density than on VM hypervisors. The only drawback is that the container must be the same OS as the host (Linux in this case) and it depends on the host for kernel functionality (e.g. modules etc).

    In this guide we will build an LXD container with two virtual NICs which are attached to the physical NIC of it’s host using bridged networking.


    • An Ubuntu 16.04 host with two physical NICs

    Prepare host networking

    Install dependencies

    # apt -y install bridge-utils

    Setup networking on the host

    There are two interfaces on the host enp3s0 and enp5s0. The first one, enp3s0 is the primary and connects to the main, DHCP enabled, internal network. The second one is connected to an isolated internal network where some critical services are running. There is no DHCP in the isolated network.

    Prepare your /etc/network/interfaces configuration file like this:

    # The loopback network interface 
    auto lo
    iface lo inet loopback
    # The main Bridge
    auto br0
    iface br0 inet dhcp
        bridge-ifaces enp3s0
        bridge-ports enp3s0
        up ip link set enp3s0 up
    # The primary network interface
    iface enp3s0 inet manual
    # The secondary Bridge
    auto br1
    iface br1 inet manual
            bridge-ifaces enp5s0
            bridge-ports enp5s0
            up ip link set enp5s0 up
    # The secondary network interface
    iface enp5s0 inet manual

    Setup LXC/ LXD

    Installation of LXD

    # apt -y install lxd

    Prepare a new profile

    We need a profile with two NICs. First create a new profile:

    # lxc profile copy default dualnic

    Then edit the new profile with lxc profile edit dualnic:

      user.network_mode: link-local
    description: Dual nic profile
        name: eth0
        nictype: bridged
        parent: br0
        type: nic
        name: eth1
        nictype: bridged
        parent: br1
        type: nic
    name: dualnic

    The names of the virtual interfaces of the container will be eth0 for the primary and eth1 for the secondary.

    Launch the container

    Now we want to launch a Debian jessie container, which we will retrieve from the prepared images on the

    # lxc launch images:debian/jessie mycontainer -p dualnic

    List the container:

    # lxc list
    |    NAME     |  STATE  |         IPV4         | IPV6 |    TYPE    | SNAPSHOTS |
    | mycontainer | RUNNING | (eth0) |      | PERSISTENT | 0         |

    The IP listed above was set by the DHCP server in the primary network.

    Connect to the container:

    # lxc exec mycontainer bash

    Setup container’s networking

    Edit /etc/network/interfaces inside our container:

    auto lo
    iface lo inet loopback
    auto eth0
    iface eth0 inet dhcp
    auto eth1
    iface eth1 inet static
            up ip route add  via dev eth1
            up ip route add  via dev eth1

    The routes and are internal routes that need to be reached though the secondary network.

    Take a clean snapshot

    Before you start working on your container, it is a good idea to get a clean snapshot, so you can revert to it, in case you mess something up.

    # lxc snapshot mycontainer

    If you want to learn more about the and features I urge you to read the excellent introduction to LXD 2.0 by Stéphane Graber



    Installing Rocket.Chat on Debian

    Rocket.Chat is a free/open source software for team collaboration. It is a full featured platform and an ideal alternative to Slack, for organizations that are dedicated to the Free Software philosophy.

    In this guide we will demonstrate how you can setup Rocket.Chat for your organization.


    • A Debian stretch VM or server.
    • A FQDN pointing to the system’s IP. We will be using throughout this guide.

    Installation of

    Install the Snappy package manager

    Snappy is not installed on Debian by default, so we need to install it:

    # apt install snapd ca-certificates

    Install Rocket.Chat

    # snap install rocketchat-server

    Check its status:

    # systemctl status snap.rocketchat-server.rocketchat-server.service
    ● snap.rocketchat-server.rocketchat-server.service - Service for snap application rocketchat-server.rocketchat-server
       Loaded: loaded (/etc/systemd/system/snap.rocketchat-server.rocketchat-server.service; enabled; vendor preset: enabled)
       Active: active (running) since Tue 2017-01-03 12:27:50 PST; 12min ago
     Main PID: 24891 (node)
        Tasks: 10 (limit: 4915)
       CGroup: /system.slice/snap.rocketchat-server.rocketchat-server.service
               └─24891 node /snap/rocketchat-server/326/main.js
    Jan 03 12:27:50 rocket systemd[1]: Started Service for snap application rocketchat-server.rocketchat-server.

    Check its port (default is 3000):

    # ss -lnptu | grep 3000
    tcp    LISTEN     0      128       *:3000                  *:*                   users:(("node",pid=24891,fd=13))

    Looks OK

    Configure TLS

    Install nginx

    The core application does not support TLS so we will be setting up an nginx reverse proxy on top of it.

    Install NGINX and certbot from Let’s Encrypt:

    # apt -y install nginx python-certbot-nginx

    Create the VirtualHost

    We need to create this file: /etc/nginx/sites-available/

    # Upstreams
    upstream backend {
    # HTTP Server
    server {
        listen 80;
        error_log /var/log/nginx/rocketchat.access.log;
        location / {
            proxy_http_version 1.1;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection "upgrade";
            proxy_set_header Host $http_host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forward-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forward-Proto http;
            proxy_set_header X-Nginx-Proxy true;
            proxy_redirect off;

    Enable the VirtualHost:

    cd /etc/nginx/sites-enabled/
    ln -s ../sites-available/
    systemctl reload nginx

    Generate the certificate

    certbot --nginx run -d
    • Enter email address:
    • Agree to the ToS
    • Enforce HTTPS: Secure

    The VirtualHost file (/etc/nginx/sites-available/ should look like this after the creation of the Let’s Encrypt certificate:

    # Upstreams
    upstream backend {
    server {
        listen 80;
        error_log /var/log/nginx/rocketchat.access.log;
        location / {
            proxy_http_version 1.1;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection "upgrade";
            proxy_set_header Host $http_host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forward-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forward-Proto http;
            proxy_set_header X-Nginx-Proxy true;
            proxy_redirect off;
        listen 443 ssl; # managed by Certbot
    ssl_certificate /etc/letsencrypt/live/; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/; # managed by Certbot
    ssl_session_cache shared:le_nginx_SSL:1m; # managed by Certbot
    ssl_session_timeout 1440m; # managed by Certbot
    ssl_protocols TLSv1 TLSv1.1 TLSv1.2; # managed by Certbot
    ssl_prefer_server_ciphers on; # managed by Certbot
        if ($scheme != "https") {
            return 301 https://$host$request_uri;
        } # managed by Certbot

    Now visit the website to test it: (it should redirect you to

    Creating an admin account

    Register a new account. You will get this warning:

    WARNING: the setting site URL is configured to http://localhost and you are accessing from do you want to change to

    You should ofcourse answer ‘Yes’.

    This first user created is an admin user. You can set global preferences from Now users can visit the website and register with it. You may wish to Allow Notifications when you are prompted by your browser on your first visit to the site. Rocket.Chat supports many other authentication backends, including LDAP which is described in the next step.

    Besides the web service you can also download native applications for Linux, Windows, Mac OS X, Android and iOS.

    Configure LDAP

    This is an optional step, but recommended if your organization has an LDAP or Active Directory setup. In this example we are using the Fusiondirectory setup from our previous guide.

    Create a service account for, using the DSA module of Fusiondirectory:

    • Username: cn=rocketchat,ou=dsa,dc=example,dc=com
    • Password: MySecretCombination

    Now go to using an admin account and set these:

    • Enable: True
    • Login Fallback: True
    • Host:
    • Port: 389
    • Encryption: StartTLS
    • CA Cert: Paste the contents of your internal ROOT CA certificate ( for example)
    • Reject Unauthorized: True
    • Domain Base: ou=people,dc=example,dc=com
    • Use Custom Domain Search: False
    • Domain Search User: cn=rocketchat,ou=dsa,example,dc=com
    • Domain Search Password: MySecretCombination
    • Domain Search User ID: uid
    • Domain Search Object Class: person
    • Domain Search Object Category: Leave Empty
    • Username Field: Leave Empty

    Leave the default settings for the rest and press the SAVE CHANGES button

    You can use the TEST CONNECTION button to test the connection.

    You can now try to login using your LDAP username and password.



    Installing the Exodus MOD on OnePlus 2

    Less than a year ago I was attracted by the value for money offer of OnePlus 2 and became a proud owner. Being paranoid about Google tracking, I disabled most Google apps. Alas, some apps were impossible to disable. I assumed that this was caused by their dependencies with other core applications. Google play services was one them, but I never created an account with Google and never synced anything with them.

    Time went by and it happened that data over mobile was accidentally enabled. And then I noticed from the mobile data traffic statistics, that Google Play services was creating traffic even without a Google account! Why does this happens its beyond my perception, but anyone is allowed to guess based on [recent history]( "PRISM Surveillance program"). There is an option to disable background traffic on the stock Android ROM (OxygenOS) but that works only when data over mobile is enabled. With Wi-Fi enabled, Google Play services keeps on sending suspicious traffic, back to mother Google.

    So I decided to look for alternatives to replace OxygenOS with a Google-free Android ROM. These are the options I have investigated:

    • Replicant:
      This seems to be the more privacy respecting Android MOD. No support for OnePlus 2, alas!
    • AOKP:
      This is an interesting MOD with lots of features. There are recent nightly builds for OnePlus 2. I tried to install it my Phone but gave an error when I tried to sideload it.
    • CyanogenMOD:
      A popular Android MOD that was recently discontinued. A fork by the name LineageOS is taking over. No image downloads yet.<br />
      UPDATE (2-Jan-2016): There are some experimental LineageOS images here.
    • Paranoid Android:
      Another successful Android MOD with close ties to OnePlus. It boasts some interesting features. Officially supports all OnePlus models except the latest OnePlus 3T. I tried the OnePlus 2 image but the phone stack to the OnePlus logo boot screen.
    • Exodus:
      This is a minimalistic Android MOD. It is based on AOSP and is free from Google Apps. This is the only MOD I managed to get it working on my OnePlus 2.

    So I decided to go with Exodus. This guide describes the procedure and preparations I followed in order to flash the latest Exodus nightly build for OnePlus 2.

    DISCLAIMER: This guide could renter your device a luxurious brick! Backup everything before you continue. The author of this guide will not be liable for any damages you may cause on your device or any data lost. Proceed at your own risk!

    Now we got that out of the way, let’s continue.


    • A PC. In this guide we are using Debian/Ubuntu as the PC’s Operating System but this can work with other Operating Systems, with minor adaptations.
    • An OnePlus 2 smartphone. It could possibly be used for other devices too, but I have only tested this on OnePlus 2.
    • The Android Debug Bridge (ADB). This is part of the Android SDK. On Debian/Ubuntu you can install it with apt install android-tools-adb.
    • A Type-C USB cable to connect the phone to your PC.

    Make your device detectable in Linux

    There is some process we need to follow so that the OnePlus 2 device is detectable by ADB

    Enable Usb Debugging

    To Enable USB Debugging we need to first enable the Developer Options:

    • Go into Settings
    • Dive into the About phone option
    • Tap 7 times on the Build number option
    • Go back and tap on Developer Options
    • Enable USB debugging and OEM unlock

    Enable detection of device under Linux

    First ensure that the device is connected:

    # lsusb
     Bus 003 Device 039: ID 2a70:f003  

    The device ID for OnePlus 2 is 0x2a70. Set this in * ~/.android/adb_usb.ini*:

    # echo "0x2a70" >> ~/.android/adb_usb.ini

    Download the udev rules files (Thanks Nicolas Bernaerts):

    # wget --header='Accept-Encoding:none' -O /etc/udev/rules.d/51-android.rules
    # chmod a+r /etc/udev/rules.d/51-android.rules
    # wget --header='Accept-Encoding:none' -O /etc/udev/rules.d/69-mtp.rules
    # chmod a+r /etc/udev/rules.d/69-mtp.rules

    Restart the udev and ADB services:

    # systemctl restart udev
    # adb kill-server
    # adb start-server

    NOTE: make sure USB Debugging is enabled otherwise you will still not be able to see the device!

    Verify that the device is present:

    # adb devices 
    List of devices attached 
    da0afea7        unauthorized

    Seems OK.

    Backup your data and stock image

    Since we are not using Google’s services we will need to manually backup all important data such as:

    • Export contacts on a .vcf file.
    • Save Pictures and Videos from the phone on your PC
    • Backup every other Applacation data which is important to you.

    You can also backup your entire system with ADB:

    # adb backup -f oneplus2.bck -apk -shared -all

    This will take some time depending on the size of your data.

    You can later restore your system back to normal, using this command:

    # adb restore oneplus2.bck

    Prepare the recovery image

    Download Prepare the First Aid kit

    This is a bundle that includes all the files needed to bring life to a bricked OnePlus 2 device. It includes a recovery image which we will use to install Exodus (or any other image you wish) on the device.

    # wget -O ''
    # unzip

    All the necessary files are in the newly created, Firstaid directory.

    Download TWRP Custom recovery

    The recovery image that comes with Firstaid is somewhat outdated. We will download a more recent version of it and replace it in the Firstaid directory. You can download the more recent TWRP image from here. Do not use wget or other command line tools, just a normal browser to download it.

    NOTE: There are more recent versions than 3.0.2-0 like 3.0.2-1 and 3.0.2-2. You can try those if you feel lucky, but be warned! Those versions did not work on my phone. You can see all the past and resent images here.

    Verify the downloaded image:

    # wget -O twrp-public.asc
    # gpg --import twrp-public.asc
    # wget
    # gpg --verify twrp-3.0.2-0-oneplus2.img.asc twrp-3.0.2-0-oneplus2.img

    If you get Good signature from &quot;TeamWin &lt;admin>&quot; that means the image is correct. Now replace the TWRP image that comes with Firstaid with this one:

    # cp twrp-3.0.2-0-oneplus2.img Firstaid/twrp.img

    Flash the recovery image

    Reboot to fastboot mode:

    # adb reboot-bootloader

    Alternatively you can poweroff the OnePlus 2 and press the Volume UP + Power buttons simultaneously.

    Verify the presence of the device:

    # fastboot devices
    da0afea7               fastboot

    Unlock the phone:

    fastboot oem unlock

    Flash Firstaid with the recent TWRP recovery image:

    # cd Firstaid
    # ./

    Now unplug the phone from the PC, poweroff and the press the Volume DOWN + Power buttons simultaneously. This will bring your phone into TWRP recovery.

    Flashing the Exodus image

    Download Exodus image and verify

    Download the latest Exodus image for OnePlus 2 here:

    # wget
    # wget 

    Verify that the download is correct:

    # cat ; md5sum
    35dcf9ea73648682a36e673f5ed8f0eb  /android/exodus-6.0/out/target/product/oneplus2/

    Seems OK

    Plug the phone back to the PC and ensure that it is detectable by ADB:

    # adb devices 
    List of devices attached 
    da0afea7        device

    Flash the Exodus image

    Follow these steps:

    • Wipe old data: Select Wipe and then Swipe to Factory Reset. You may need to format the system if the previous system was encrypted.
    • Enter the Sideload mode: From the TWRP start menu select Advanced then ADB Sideload and then Swipe to Start Sideload
    • From the PC’s CLI run the following command:
    # adb sideload

    Wait and then reboot into the new Exodus system when done.

    Optional steps

    Install F-Droid:

    By default Exodus has a minimal set of apps. Since we are not using Google Apps we will need to install F-Droid:

    # wget
    # adb install FDroid.apk

    Lock your Phone

    Setup a PIN or Pattern to lock the screen of your phone when not in use: Settings -> Security -> Screen Lock. Avoid fingerprint as it can be easily bypassed.

    Encrypt phone

    Encrypting your phone will protect your data if it gets stolen or confiscated. These are the steps Settings -> Security -> Encrypt phone. Your phone will need to be plugged to charger and charged to 80% or above, otherwise the system will refuse to start the encryption process.

    Restoring the Stock OxygenOS System

    If you decide that you don’t like Exodus or any other MOD that you have installed, you can restore your phone back to the stock OxygenOS. These instructions can also be used to restore your phone’s functionality after you have accidentally bricked it.

    Download necessary images

    Download the stock OxygenOS 3.0.2 image from here. Verify the download with:

    # echo 46b1fde116275d83d05c2dd89422069f ; md5sum

    Download the upgrade patch for Oxygen 3.1.0 from here. Verify the download with:

    # echo 9cfa9a2a4c7fada6f9db79ea660251d0 ; md5sum 

    Optionally you can download the SuperSU image if you would like your OxygenOS rooted:

    # wget -O ''

    Flash Recover image

    First we need to restore the recovery ROM from Firstaid:

    # cd Firstaid
    # ./

    Flash the Oxygen Images.

    Before we install the OxygenOS image it is recommended to wipe the phone: From the TWRP menu select Wipe and then Swipe to factory reset. If the system was previously encrypted you will need to use TWRP to format it before the wipe.

    Then we need to set the device into Sideload mode: Select Advanced -> ADB Sideload -> Swipe to Start Sideload.

    First install the OxygenOS 3.0.2 image:

    adb sideload

    Then re-enable ADB Sideload and load the Oxygen 3.2.0 patch:

    adb sideload

    Optionally you can also load the SuperSU application as well

    adb sideload

    Finally reboot into the new system and enjoy your freshly formatted phone.



    Creating an authoritative-only DNS system for your domain

    Most registrars they provide a DNS service when you purchase a domain name. But having your own DNS servers means more control to you. And if you are an aspiring sysadmin, you will find it fun and educational. We will be using BIND 9 which is, by far the most popular DNS implementation.


    We will need two systems (VMs or containers) preferably on different geographic locations and different providers. One will be the master and the other system, the slave. This guide works for recent Debian or Ubuntu systems.

    Some assumptions:

    • Master DNS:
      • Hostname:
      • IP:
    • Slave DNS:
      • Hostname:
      • IP:
    • Webserver:
      • Hostname: ( is an alias)
      • IP:
    • Main mailserver:
      • Hostname: ({mail,smtp,pop,imap,webmail} are aliases)
      • IP:
    • Backup mailserver:
      • Hostname:
      • IP:


    Setup the /etc/hosts file

    On master’s /etc/hosts: ns1

    On slave’s /etc/hosts: ns2

    Installing BIND

    NOTE: all commands must be applied to both master and slave unless otherwise stated

    apt-get -y install bind9 bind9utils

    Allow port 53:

    ufw allow 53

    Configure the global options

    Make the following changes in the /etc/bind/named.conf.options of both servers:

    --- /etc/bind/named.conf.options        2016-12-12 14:44:57.163515708 -0500
    +++ /etc/bind/    2016-12-12 14:52:29.749268250 -0500
    @@ -1,5 +1,7 @@
     options {
            directory "/var/cache/bind";
    +       recursion no;
    +       allow-transfer { none; };
            // If there is a firewall between you and nameservers you want
            // to talk to, you may need to fix the firewall to allow multiple

    Configure the local options

    On master’s /etc/bind/named.conf.local:

    --- /etc/bind/named.conf.local  2016-12-12 20:06:27.000000000 +0000
    +++ /etc/bind/      2016-12-12 20:07:03.000000000 +0000
    @@ -6,3 +6,8 @@
     // organization
     //include "/etc/bind/zones.rfc1918";
    +zone "" {
    +    type master;
    +    file "/etc/bind/";
    +    allow-transfer {; };

    On slave’s /etc/bind/named.conf.local:

    --- /etc/bind/named.conf.local  2016-11-01 13:02:24.000000000 -0400
    +++ /etc/bind/      2016-12-12 15:09:47.445235343 -0500
    @@ -6,3 +6,8 @@
     // organization
     //include "/etc/bind/zones.rfc1918";
    +zone "" {
    +    type slave;
    +    file "";
    +    masters {; };

    Create the zone file

    On master server create the zone file (/etc/bind/

    $TTL 3600
    @    IN    SOA (
                                                180 )
    ; NS Records
    @       300    IN      NS    
    @       300    IN      NS    
    ; MX Records
    @       300    IN      MX      10
    @       300    IN      MX      20
    ; Address records
    @       300    IN      A     
    ns1     300    IN      A     
    ns2     300    IN      A     
    mx1     300    IN      A     
    mx1     300    IN      A     
    ; Alias (Canonical Name) records
    www     300    IN      CNAME 
    mail    300    IN      CNAME 
    smtp    300    IN      CNAME 
    imap    300    IN      CNAME 
    pop     300    IN      CNAME 
    webmail 300    IN      CNAME 
    ; TXT records
    @       300    IN      TXT             "v=spf1 a mx ?all"

    Verify the global configuration

    Run the named-checkconf command on both servers. If you get any errors you should fix them before proceeding.

    Verify the zone configuration

    Run the following command on the master server:

    named-checkzone /etc/bind/ 
    zone loaded serial 2016121201

    If you get ‘OK’ then your setup is correct, otherwise you should fix it before proceeding.

    Restart bind and test your servers

    systemctl restart bind9.service

    Now test if your servers resolve your records.

    The master:

    dig @
    ;; ANSWER SECTION:   300 IN  CNAME    300 IN  A

    The slave:

    dig @
    ;; ANSWER SECTION:   300 IN  CNAME    300 IN  A

    If you get any errors you can check your syslog file (/var/log/syslog).


    After you have tested that everything is OK, it is time to tell your registrar about the new servers. This is called setting the glue records and you should consult the documentation of your registrar on how to do that. Ask support if you have any trouble.



    How to remotely decrypt a LUKS encrypted Debian/Ubuntu System

    In this guide we will show how you can remotely decrypt a headless Debian or Ubuntu Linux system, that has been encrypted with LUKS.


    • A LUKS encrypted Debian jessie or Ubuntu xenial system
    • Keyboard and monitor for the initial system setup
    • Allow SSH root access on the decrypted system using public key authentication
    • Use a different port for ssh (assuming port 4422) on the decrypted system

      NOTE: using a different port than the standard SSH port (22) serves a double purpose. For once, you will not received the scary WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! message every time you will try to remotely unlock the system and as an additional bonus you will get less SSH attacks on the active system.

    Installing dropbear

    Dropbear is a lightweight SSH server especially suitable for initial ramdisk (initrd) environments and other lightweight systems.

    Install dropbear:

    # apt -y install dropbear

    Setup public key authentication for dropbear

    Create the homedir for the root user and the SSH configuration directory:

    # mkdir -p /etc/initramfs-tools/root/.ssh

    Append your client SSH pubkey to authorized_keys:

    # cat ~/.ssh/ | ssh -p 4422 root@encrypted-system "cat >> /etc/initramfs-tools/root/.ssh/authorized_keys"

    Setup a static IP for the unlock environment

    This step is optional but highly recommended if you are setting up a static, permanent service. If you skip this step DHCP will kick in, provided you have a DHCP Server in your environment.

    Run this command to update the /etc/initramfs-tools/initramfs.conf configuration file:

    echo IP= >> /etc/initramfs-tools/initramfs.conf

    Explanation of the different fields:

    NOTE: there are two successive colons (::) after the host_ip.

    Setup the unlock script

    Copy the following text in /etc/initramfs-tools/hooks/

    # By Stinky Parkia
    prereqs() {
        echo "$PREREQ"
    case "$1" in
        exit 0
    . "${CONFDIR}/initramfs.conf"
    . /usr/share/initramfs-tools/hook-functions
    if [ "${DROPBEAR}" != "n" ] && [ -r "/etc/crypttab" ] ; then
        cat > "${DESTDIR}/bin/unlock" < < EOF
    if PATH=/lib/unlock:/bin:/sbin /scripts/local-top/cryptroot; then
        kill \`ps | grep cryptroot | grep -v "grep" | awk '{print \$1}'\`
        # following line kill the remote shell right after the passphrase has
        # been entered.
        kill -9 \`ps | grep "\-sh" | grep -v "grep" | awk '{print \$1}'\`
        exit 0
    exit 1
        chmod 755 "${DESTDIR}/bin/unlock"
        mkdir -p "${DESTDIR}/lib/unlock"
        cat > "${DESTDIR}/lib/unlock/plymouth" < < EOF
    [ "\$1" == "--ping" ] && exit 1
    /bin/plymouth "\$@"
        chmod 755 "${DESTDIR}/lib/unlock/plymouth"
        echo To unlock root-partition run "unlock" >> ${DESTDIR}/etc/motd

    Make the script executable:

    # chmod +x /etc/initramfs-tools/hooks/

    Apply the configuration

    Apply the changes in the initial ramdisk:

    # update-initramfs -u

    Reboot the system:

    # reboot

    Remotely unlock the system

    From your client, SSH into the initial ramdisk:

    ssh root@encrypted-system 

    If everything is correct you will be greeted by this MOTD:

    To unlock root-partition run unlock
    BusyBox v1.22.1 (Ubuntu 1:1.22.0-15ubuntu1) built-in shell (ash)
    Enter 'help' for a list of built-in commands.

    Unlock the system and boot into it:

    # unlock
    Please unlock disk sda3_crypt: 

    You will get the following message and you will exit the remote shell if successful:

    cryptsetup: sda3_crypt set up successfully
    Connection to closed.

    You can now login to the active Linux system using the alternative port 4422:

    ssh -p 4422 root@encrypted-system

    If you can login successfully to your system you can remove the keyboard and monitor and hide your system somewhere where the Sun does not shine :).

    Thanks to Stinky Parkia for the excellent guide and the brilliant unlock script.



    Setting up a Postfix/Dovecot mail system with an LDAP/Fusiondirectory backend

    This guide is about setting up a Postfix/Dovecot system using LDAP/Fusiondirectoory as a backend.


    • Install an LDAP/Fusiondirectory infrastructure
    • A DNS A Record: 300 IN A
    • A DNS PTR Record: 300 IN PTR
    • A DNS MX Record (Actually more than one): 300 IN MX 5

    Install FusionDirectory Plugins

    • Install the Mail plugin:
      apt -y install fusiondirectory-plugin-mail fusiondirectory-plugin-mail-schema
      fusiondirectory-insert-schema -i /etc/ldap/schema/fusiondirectory/mail-fd.schema
      fusiondirectory-insert-schema -i /etc/ldap/schema/fusiondirectory/mail-fd-conf.schema
    • Install the Alias plugin:
      apt -y install fusiondirectory-plugin-alias fusiondirectory-plugin-alias-schema
      fusiondirectory-insert-schema -i /etc/ldap/schema/fusiondirectory/alias-fd-conf.schema
      fusiondirectory-insert-schema -i /etc/ldap/schema/fusiondirectory/alias-fd.schema
    • Install the Postfix plugin:
      apt -y install fusiondirectory-plugin-postfix fusiondirectory-plugin-postfix-schema
      fusiondirectory-insert-schema -i /etc/ldap/schema/fusiondirectory/postfix-fd.schema

    Setup mail services:

    • Enter the server configuration (Systems plugin)
    • From the ‘Services’ tab create a ‘Postfix (SMTP)’ and an ‘IMAP/POP3 generic’ service

    • Add mail capability to all normal users:

      • Click the ‘Mail’ tab of a user and then press ‘Add Mail settings’
    • Fill in the ‘Primary Address. field and select as the server.

  • Add All necessary distribution lists and redirections from ‘Aliases’

  • Setup postfix

    • Create a service account for postfix using the ‘DSA’ plugin in *FusionDirectory’. It should look like this:

      dn: cn=postfix,ou=dsa,dc=example,dc=com
      cn: postfix
      userPassword:: yeduyt2732tet87eoiewoi32t4873t4387f7gf47gf49i6=
      structuralObjectClass: organizationalRole
      entryUUID: 280427ce-9a54-1035-8e48-bf1fd814366b
      creatorsName: cn=admin,dc=example,dc=com
      createTimestamp: 20160419082627Z
      objectClass: organizationalRole
      objectClass: top
      objectClass: simpleSecurityObject
      entryCSN: 20160419082628.006263Z#000000#000#000000
      modifiersName: cn=admin,dc=example,dc=com
      modifyTimestamp: 20160419082628Z

    • Install postfix:
      apt -y install postfix postfix-pcre postfix-ldap

      When you are prompted about "General type of mail configuration:" select "No configuration"

    • Prepare the /etc/postfix/ file:

    smtpd_banner = $myhostname ESMTP $mail_name
    biff = no
    append_dot_mydomain = no
    readme_directory = no
    smtpd_tls_security_level = may
    smtpd_tls_auth_only = yes
    smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
    smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
    smtpd_tls_dh512_param_file = ${config_directory}/certs/dh_512.pem
    smtpd_tls_dh1024_param_file = ${config_directory}/certs/dh_1024.pem
    tls_random_source = dev:/dev/urandom
    smtpd_tls_loglevel = 0
    smtpd_client_new_tls_session_rate_limit = 10
    smtpd_tls_exclude_ciphers =
    myhostname =
    alias_maps = hash:/etc/aliases
    alias_database = hash:/etc/aliases
    myorigin = /etc/mailname
    mydestination = $myhostname,, localhost.localdomain, localhost
    relayhost =
    mynetworks = [::ffff:]/104 [::1]/128
    mailbox_size_limit = 0
    recipient_delimiter = +
    inet_interfaces = all
    inet_protocols = all
    local_transport = local
    postscreen_greet_action = enforce
    smtpd_recipient_restrictions =
        warn_if_reject reject_non_fqdn_hostname
        warn_if_reject reject_non_fqdn_sender
        check_sender_ns_access cidr:/etc/postfix/drop.cidr
        check_sender_mx_access cidr:/etc/postfix/drop.cidr
    smtpd_data_restrictions = reject_multi_recipient_bounce
    smtpd_sender_restrictions =
    smtpd_helo_restrictions =
        check_helo_access pcre:/etc/postfix/identitycheck.pcre
    disable_vrfy_command = yes
    smtpd_helo_required = yes
    smtpd_delay_reject = no
    smtpd_client_restrictions = check_client_access cidr:/etc/postfix/drop.cidr
    message_size_limit = 51200000
    • Prepare the rest of the configuration files:

      • Prepare the virtual domains file:
        cat > /etc/postfix/virtual_domains &lt; &lt; EOF
         # Domain                Anything
      • Prepare the virtual recipients file:
        cat > /etc/postfix/ &lt; &lt; EOF
        bind = yes
        bind_dn = cn=postfix,ou=dsa,dc=example,dc=com
        bind_pw = NotTheRealPassword
        server_host = ldap://
        search_base = ou=people,dc=example,dc=com
        domain =
        query_filter = (mail=%s)
        result_attribute = mail
        start_tls = yes
        version = 3
      • Prepare the virtual aliases file:
        cat > /etc/postfix/ < < EOF
        bind = yes
        bind_dn = cn=postfix,ou=dsa,dc=example,dc=com
        bind_pw = NotTheRealPass
        server_host = ldap://
        search_base = ou=alias,dc=example,dc=com
        domain =
        query_filter = (mail=%s)
        result_attribute = gosaMailAlternateAddress, gosaMailForwardingAddress
        start_tls = yes
        version = 3
      • Prepare the identity check file:
        cat > /etc/postfix/identitycheck.pcre &lt; &lt; EOF
        # Identity (RegEx)              Action
        /^(mail\.example\.com)$/       REJECT Hostname Abuse: $1
        /^(1\.2\.3\.4)$/                REJECT Hostname Abuse: $1
        /^(\[1\.2\.3\.4\])$/            REJECT Hostname Abuse: $1
      • Prepare the blacklist file:
        cat > /etc/postfix/drop.cidr &lt; &lt; EOF
        # IP/CIDR                       Action
                             REJECT Blacklisted
    • Generate the virtual domains hashmap:
      postmap hash:/etc/postfix/virtual_domains
    • Start postfix:
      systemctl start postfix


      ss -lnptu | grep master
      tcp    LISTEN     0      100    *:25      *:*      users (("master",pid=15539,fd=12))
    • Enable support for smtps (port 465) and submission (port 587):

      Uncomment the following lines from /etc/postfix/

      submission inet n       -       -       -       -       smtpd
      smtps     inet  n       -       -       -       -       smtpd

      Restart postfix:

      systemctl restart postfix


      ss -lnptu | grep master
      tcp    LISTEN     0      100    *:587     *:*      users:(("master",pid=15854,fd=16))
      tcp    LISTEN     0      100    *:465     *:*      users:(("master",pid=15854,fd=19))
      tcp    LISTEN     0      100    *:25      *:*      users:(("master",pid=15854,fd=12))
    • Take precautions for perfect forward secrecy:
      mkdir /etc/postfix/certs
      cd /etc/postfix/certs
      openssl dhparam -2 -out dh_512.pem 512
      openssl dhparam -2 -out dh_1024.pem 1024
      chmod 600 dh_*
    • Lookup test:
      postmap -q ldap:/etc/postfix/
    • Open SMTP, SMTPS ans Submission ports:
      ufw allow 25/tcp
      ufw allow 465/tcp
      ufw allow 587/tcp

    Install and configure dovecot

    • Create a service account for dovecot using the ‘DSA’ plugin in *FusionDirectory’. It should look like this:
      dn: cn=dovecot,ou=dsa,dc=example,dc=com
      cn: dovecot
      userPassword:: ljsdewd98dej932j98dxjud8x3jx9843xj8943j438439e3=
      structuralObjectClass: organizationalRole
      entryUUID: 4d0d7174-9a54-1035-8e49-bf1fd814366b
      creatorsName: cn=admin,dc=example,dc=com
      createTimestamp: 20160419082730Z
      objectClass: organizationalRole
      objectClass: top
      objectClass: simpleSecurityObject
      entryCSN: 20160419082730.138012Z#000000#000#000000
      modifiersName: cn=admin,dc=example,dc=com
      modifyTimestamp: 20160419082730Z
    • Install dovecot:
      apt -y install dovecot-core dovecot-imapd dovecot-pop3d dovecot-lmtpd dovecot-ldap
    • Make the following changes in /etc/dovecot/conf.d/10-ssl.conf:
    ssl = required
    ssl_cert = 
    service imap-login {
      inet_listener imap {
        port = 143
      inet_listener imaps {
        port = 993
        ssl = yes
    service pop3-login {
      inet_listener pop3 {
        port = 110
      inet_listener pop3s {
        port = 995
        ssl = yes
    service auth {
      unix_listener auth-userdb {
        mode = 0777
        user = dovecot
        group = dovecot
    • Add the vmail user in the system:

      addgroup --system --gid 5000 vmail
      adduser --system --home /srv/vmail --uid 5000 --gid 5000 --disabled-password --disabled-login vmail

    • Restart dovecot:
      systemctl restart dovecot


      netstat -lnptu | grep dovecot
      tcp        0      0   *               LISTEN      20894/dovecot   
      tcp        0      0   *               LISTEN      20894/dovecot   
      tcp        0      0   *               LISTEN      20894/dovecot   
      tcp        0      0   *               LISTEN      20894/dovecot   
      tcp6       0      0 :::993                  :::*                    LISTEN      20894/dovecot   
      tcp6       0      0 :::995                  :::*                    LISTEN      20894/dovecot   
      tcp6       0      0 :::110                  :::*                    LISTEN      20894/dovecot   
      tcp6       0      0 :::143                  :::*                    LISTEN      20894/dovecot  
    • Check if you can login:
    openssl s_client -connect localhost:993
    <output ommitted...>
    a1 LOGIN theo MyNotSoSecretPass
    a3 LOGOUT
    * BYE Logging out
    a2 OK Logout completed.
    • Enable IMAP, IMAPS, POP3 and POP3S ports:

      ufw allow 110/tcp
      ufw allow 143/tcp
      ufw allow 993/tcp
      ufw allow 995/tcp

    • Tell postfix to deliver mail using dovecot:
      • Add the following lines at the end of /etc/postfix/
        dovecot   unix  -       n       n       -       -       pipe
          flags=ODRhu user=vmail:vmail argv=/usr/lib/dovecot/deliver -e -f ${sender} -d ${recipient}
      • Add these attributes in /etc/postfix/
        virtual_transport = dovecot
        dovecot_destination_recipient_limit = 1
    • Restart postfix and dovecot:
      systemctl restart postfix dovecot

    Install SASL for SMTP AUTH

    • Create a service account for saslauthd using the ‘DSA’ plugin in *FusionDirectory’. It should look like this:
      dn: cn=saslauthd,ou=dsa,dc=example,dc=com
      cn: saslauthd
      userPassword:: ejdoedoifj9ewufd9843e9ejfd98je938jcr9843843=
      structuralObjectClass: organizationalRole
      entryUUID: 61143234-9a54-1035-8e4a-bf1fd814366b
      creatorsName: cn=admin,dc=example,dc=com
      createTimestamp: 20160419082803Z
      objectClass: organizationalRole
      objectClass: top
      objectClass: simpleSecurityObject
      entryCSN: 20160419082803.738357Z#000000#000#000000
      modifiersName: cn=admin,dc=example,dc=com
      modifyTimestamp: 20160419082803Z
    • Install SASL:
      apt -y install libsasl2-2 sasl2-bin
    • Create the /etc/postfix/sasl/smtpd.conf file:
      cat > /etc/postfix/sasl/smtpd.conf < < EOF
      log_level: 3
      pwcheck_method: saslauthd
      mech_list: PLAIN LOGIN
    • Make the following changes in /etc/default/saslauthd:
      OPTIONS="-c -m /var/spool/postfix/var/run/saslauthd"
    • Create the /etc/saslauthd.conf file:
      cat > /etc/saslauthd.conf < < EOF
      ldap_servers: ldap://
      ldap_bind_dn: cn=saslauthd,ou=dsa,dc=example,dc=com
      ldap_bind_pw: MySecretPass
      ldap_timeout: 10
      ldap_time_limit: 10
      ldap_scope: sub
      ldap_search_base: ou=people,dc=example,dc=com
      ldap_auth_method: bind
      ldap_filter: (&(uid=%u)(mail=*))
      ldap_debug: 0
      ldap_verbose: off
      ldap_ssl: yes
      ldap_starttls: no
      ldap_referrals: yes
    • Add the postfix user in the sasl group:
      usermod -aG sasl postfix
    • Add these attributes in /etc/postfix/
      smtpd_sasl_auth_enable = yes
      broken_sasl_auth_clients = yes
    • Restart saslauthd and postfix:
      systemctl restart saslauthd postfix
    • Test message delivery using SMTP AUTH:

      First you need to install swaks:

      apt -y install swaks

      Then use swaks to test message delivery:

      swaks --from --to --server --tls --auth plain --auth-user=theo
    • Test if the message has been delivered to inbox:

      First you need to install mutt:

      apt -y install mutt

      Then use mutt to test if the message has been delivered to inbox:

      mutt -f /srv/vmail/

      NOTE: When you are asked to create a ‘mail’ folder just say ‘no’.