"Honey pots" by "Nicholas" on Flickr

Adding MITM (or “Trusted Certificate Authorities”) proxy certificates for Linux and Linux-like Environments

In some work environments, you may find that a “Man In The Middle” (also known as MITM) proxy may have been configured to inspect HTTPS traffic. If you work in a predominantly Windows based environment, you may have had some TLS certificates deployed to your computer when you logged in, or by group policy.

I’ve previously mentioned that if you’re using Firefox on your work machines where you’ve had these certificates pushed to your machine, then you’ll need to enable a configuration flag to make those work under Firefox (“security.enterprise_roots.enabled“), but this is talking about Linux (like Ubuntu, Fedora, CentOS, etc.) and Linux-like environments (like WSL, MSYS2)

Start with Windows

From your web browser of choice, visit any HTTPS web page that you know will be inspected by your proxy.

If you’re using Mozilla Firefox

In Firefox, click on this part of the address bar and click on the right arrow next to “Connection secure”:

Clicking on the Padlock and then clicking on the Right arrow will take you to the “Connection Security” screen.
Certification Root obscured, but this where we prove we have a MITM certificate.

Click on “More Information” to take you to the “Page info” screen

More obscured details, but click on “View Certificate”

In recent versions of Firefox, clicking on “View Certificate” takes you to a new page which looks like this:

Mammoth amounts of obscuring here! The chain runs from left to right, with the right-most blob being the Root Certificate

Click on the right-most tab of this screen, and navigate down to where it says “Miscellaneous”. Click on the link to download the “PEM (cert)”.

The details on the Certificate Authority (highly obscured!), but here is where we get our “Root” Certificate for this proxy.

Save this certificate somewhere sensible, we’ll need it in a bit!

Note that if you’ve got multiple proxies (perhaps for different network paths, or perhaps for a cloud proxy and an on-premises proxy) you might need to force yourself in into several situations to get these.

If you’re using Google Chrome / Microsoft Edge

In Chrome or Edge, click on the same area, and select “Certificate”:

This will take you to a screen listing the “Certification Path”. This is the chain of trust between the “Root” certificate for the proxy to the certificate they issue so I can visit my website:

This screen shows the chain of trust from the top of the chain (the “Root” certificate) to the bottom (the certificate they issued so I could visit this website)

Click on the topmost line of the list, and then click “View Certificate” to see the root certificate. Click on “Details”:

The (obscured) details for the root CA.

Click on “Copy to File” to open the “Certificate Export Wizard”:

In the Certificate Export Wizard, click “Next”
Select “Base-64 encoded X.509 (.CER)” and click “Next”
Click on the “Browse…” button to select a path.
Name the file something sensible, and put the file somewhere you’ll find it shortly. Click “Save”, then click “Next”.

Once you’ve saved this file, rename it to have the extension .pem. You may need to do this from a command line!

Ubuntu or Debian based systems as an OS, or as a WSL environment

As root, copy the proxy’s root key into /usr/local/share/ca-certificates/<your_proxy_name>.crt (for example, /usr/local/share/ca-certificates/proxy.my.corp.crt) and then run update-ca-certificates to update the system-wide certificate store.

RHEL/CentOS as an OS, or as a WSL environment

As root, copy the proxy’s root key into /etc/pki/ca-trust/source/anchors/<your_proxy_name>.pem (for example, /etc/pki/ca-trust/source/anchors/proxy.my.corp.pem) and then run update-ca-trust to update the system-wide certificate store.

MSYS2 or the Ruby Installer

Open the path to your MSYS2 environment (e.g. C:\Ruby30-x64\msys64) using your file manager (Explorer) and run msys2.exe. Then paste the proxy’s root key into the etc/pki/ca-trust/source/anchors subdirectory, naming it <your_proxy_name>.pem. In the MSYS2 window, run update-ca-trust to update the environment-wide certificate store.

Ruby Installer

If you’ve obtained the Ruby Installer from https://rubyinstaller.org/ and installed it from there, assuming you accepted the default path of C:\Ruby<VERSION>-x64 (e.g. C:\Ruby30-x64) you need to perform the above step (running update-ca-trust) and then copy the file from C:\Ruby30-x64\mysys64\etc\pki\ca-trust\extracted\pem\tls-ca-bundle.pem to C:\Ruby30-x64\ssl\cert.pem

Sources:

Featured image is “Honey pots” by “Nicholas” on Flickr and is released under a CC-BY license.

"Prickily Hooks" by "Derek Gavey" on Flickr

When starting WSL2, you get “The attempted operation is not supported for the type of object referenced.”

Hello, welcome to my personal knowledgebase article 😁

I think you only get this if you have some tool or service which hooks WinSock to perform content inspection, but if you do, you need to tell WinSock to reject attempts to hook WSL2.

According to this post on the Github WSL Issues list, you need to add a key into your registry, in the path HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WinSock2\Parameters\AppId_Catalog and they mention that the vendor of “proxifier” have released a tool which creates this key. The screen shot in the very next post shows this registry key having been created.

A screenshot of a screenshot of the registry path needed to prevent WinSock from being hooked.

I don’t know if the hex ID of the “AppId_Catalog” path created is relevant, but it was what was in the screenshot, so I copied it, and created this registry export file. Feel free to create your own version of this file, and run it to fix your own issue.

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WinSock2\Parameters\AppId_Catalog\0408F7A3]
"AppFullPath"="C:\\Windows\\System32\\wsl.exe"
"PermittedLspCategories"=dword:80000000

As soon as I’d included this registry entry, I was able to access WSL OK again.

Featured image is “Prickily Hooks” by “Derek Gavey” on Flickr and is released under a CC-BY license.

"Main console" by "Steve Parker" on Flickr

Running services (like SSH, nginx, etc) on Windows Subsystem for Linux (WSL1) on boot

I recently got a new laptop, and for various reasons, I’m going to be primarily running Windows on that laptop. However, I still like having a working SSH server, running in the context of my Windows Subsystem for Linux (WSL) environment.

Initially, trying to run service ssh start failed with an error, because you need to re-execute the ssh configuration steps which are missed in a WSL environment. To fix that, run sudo apt install --reinstall openssh-server.

Once you know your service runs OK, you start digging around to find out how to start it on boot, and you’ll see lots of people saying things like “Just run a shell script that starts your first service, and then another shell script for the next service.”

Well, the frustration for me is that Linux already has this capability – the current popular version is called SystemD, but a slightly older variant is still knocking around in modern linux distributions, and it’s called SystemV Init, often referred to as just “sysv” or “init.d”.

The way that those services work is that you have an “init” file in /etc/init.d and then those files have a symbolic link into a “runlevel” directory, for example /etc/rc3.d. Each symbolic link is named S##service or K##service, where the ## represents the order in which it’s to be launched. The SSH Daemon, for example, that I want to run is created in there as /etc/rc3.d/S01ssh.

So, how do I make this work in the grander scheme of WSL? I can’t use SystemD, where I could say systemctl enable --now ssh, instead I need to add a (yes, I know) shell script, which looks in my desired runlevel directory. Runlevel 3 is the level at which network services have started, hence using that one. If I was trying to set up a graphical desktop, I’d instead be looking to use Runlevel 5, but the X Windows system isn’t ported to Windows like that yet… Anyway.

Because the rc#.d directory already has this structure for ordering and naming services to load, I can just step over this directory looking for files which match or do not match the naming convention, and I do that with this script:

#! /bin/bash
function run_rc() {
  base="$(basename "$1")"
  if [[ ${base:0:1} == "S" ]]
  then
    "$1" start
  else
    "$1" stop
  fi
}

if [ "$1" != "" ] && [ -e "$1" ]
then
  run_rc "$1"
else
  rc=3
  if [ "$1" != "" ] && [ -e "/etc/rc${$1}.d/" ]
  then
    rc="$1"
  fi
  for digit1 in {0..9}
  do
    for digit2 in {0..9}
    do
      find "/etc/rc${rc}.d/" -name "[SK]${digit1}${digit2}*" -exec "$0" '{}' \; 2>/dev/null
    done
  done
fi

I’ve put this script in /opt/wsl_init.sh

This does a bit of trickery, but basically runs the bottom block first. It loops over the digits 0 to 9 twice (giving you 00, 01, 02 and so on up to 99) and looks in /etc/rc3.d for any file containing the filename starting S or K and then with the two digits you’ve looped to by that point. Finally, it runs itself again, passing the name of the file it just found, and this is where the top block comes in.

In the top block we look at the “basename” – the part of the path supplied, without any prefixed directories attached, and then extract just the first character (that’s the ${base:0:1} part) to see whether it’s an “S” or anything else. If it’s an S (which everything there is likely to be), it executes the task like this: /etc/rc3.d/S01ssh start and this works because it’s how that script is designed! You can run one of the following instances of this command: service ssh start, /etc/init.d/ssh start or /etc/rc3.d/S01ssh start. There are other options, notably “stop” or “status”, but these aren’t really useful here.

Now, how do we make Windows execute this on boot? I’m using NSSM, the “Non-sucking service manager” to add a line to the Windows System services. I placed the NSSM executable in C:\Program Files\nssm\nssm.exe, and then from a command line, ran C:\Program Files\nssm\nssm.exe install WSL_Init.

I configured it with the Application Path: C:\Windows\System32\wsl.exe and the Arguments: -d ubuntu -e sudo /opt/wsl_init.sh. Note that this only works because I’ve also got Sudo setup to execute this command without prompting for a password.

Here I invoke C:\Windows\System32\wsl.exe -d ubuntu -e sudo /opt/wsl_init.sh
I define the name of the service, as Services will see it, and also the description of the service.
I put in MY username and My Windows Password here, otherwise I’m not running WSL in my user context, but another one.

And then I rebooted. SSH was running as I needed it.

Featured image is “Main console” by “Steve Parker” on Flickr and is released under a CC-BY license.

Building a Dual boot machine running Ubuntu 17.04 and Windows 10 with full-disk encryption

This post has been revised since it was initially published on 31st March due to errors found in the resulting build. It was also missing details on the shared data drive between the two machines, so has been amended to include that.

** WARNING ** This works for me – it might not for you!

The outcome of this build will leave you with the following:

Boot up, go through the VeraCrypt bootloader, enter a password for Windows, or press escape to load the Grub bootloader where you will boot (K|L|X|)Ubuntu(| Mate| Gnome).

The Windows environment will be encrypted with VeraCrypt, an open source Full Disk Encryption technology, while the Linux environment will be encrypted using Luks. The shared volume (between Windows and Linux) will be encrypted with VeraCrypt.

PLEASE BE AWARE THAT ANY WINDOWS 10 UPGRADES WILL FAIL TO APPLY AS IT WILL NOT RECOGNISE THE VERACRYPT FILE SYSTEM! To resolve this, decrypt the Windows volume, perform the upgrade, re-encrypt it, then transfer the new recovery ISO image to the boot volume, following the method below. Yes, this will take some time. No, you don’t need to decrypt the data volume. Yes, you can use that data volume to shunt the ISO image around.

LATE EDIT 2020-01-06: I’ve just spotted a link to this post over on Level1Techs. In that post, someone asked if the broken upgrades is still a thing. Turns out that since I wrote this in 2017, it’s not been fixed. Now, I should stress, I’ve stopped using this layout as I went all-Linux on that machine, but… it might work for you now?! Also, shout out to 92aceshigh for referencing this post, and glad something I wrote helped you! ☺

Step 1:Create your partition table

My partition table, for a 320GB Disk looks (roughly) like this:

Partition 1: 20GB – Linux /Boot (ext2, plus space for ISO files for random booting)
Partition 2: 60GB – Windows C:\ (NTFS VeraCrypt)
Partition 3: 72GB – Linux Physical Volume (LVM PV, Luks Encrypted)
– logical volume 1: 16Gb Swap (Linux Swap)
– logical volume 2: 60Gb Linux (ext4)
Partition 4: 156GB – Shared Volume (NTFS, VeraCrypt)

I performed this using GParted in the Gnome Live image using the GParted. Some rational here:

  1. The first partition also allows me to add other ISOs if I want to boot them.
  2. I have 4GB RAM, this gives me some extra space to allow me to hibernate, but also… 4Gb. Ugh.
  3. I then split my Linux and Windows partitions into two equal parts.

Step 2: Use Cryptsetup to format the disk

The following steps need to be run as root.

sudo -i

Step 2a: Format the partitions as LUKS

cryptsetup luksFormat -y -v /dev/sda3

Step 2b: Open the LUKS volume

cryptsetup luksOpen /dev/sda3 lvm-pv

Step 2c: Create the LVM Physical Volume over the LUKS volume

vgcreate vg00 /dev/mapper/lvm-pv

Step 2d: Define the LVM Logical Volumes over the LVM Physical Volume

lvcreate -n lv00_swap -L 16G vg00       # Define 16GB Swap Space
lvcreate -n lv01_root -l +100%FREE vg00 # Define the rest of vg00 as /

LEAVE YOUR TERMINAL OPEN

Step 3: Install your Linux distribution.

Note that when you perform your install, when you get to the partitioning screen, select “Manual”, and then pick out the following volumes:

/dev/mapper/vg00-lv01_root = ext4 formatted, mount point: /
/dev/mapper/vg00-lv00_swap = swap
/dev/sda1 = ext2, format, mount point: /boot

Select the boot volume of /dev/sda. But wait, I hear you say, Windows has a well know history of nuking Grub partitions… Well, we’ll sort that in a bit…

DON’T EXIT THE LIVE SESSION ONCE THE INSTALL HAS FINISHED (select “Continue Testing”).

Step 4: Make your machine actually able to boot

Go back to your terminal session.  It should still be logged in as root. We need to re-mount all the partitions…

Step 4a: Mount your volumes

mount /dev/mapper/vg00-lv01_root /target
mount /dev/sda1 /target/boot
for i in /dev /dev/pts /proc /sys /run; do sudo mount -B $i /target$i; done

Step 4b: Swap to the “Target” filesystem

chroot /target

Step 4c: Setup your volumes to prompt for cryptographic keys

echo "LinuxRoot UUID=`blkid | grep sda3 | cut -d\\\" -f2` none luks" > /etc/crypttab

Step 4d: Update the boot volume to use these changes

update-initramfs -u

Step 4e: Ensure Grub is also installed to the MBR for testing

grub-install --force /dev/sda1
chattr +i /boot/grub/i386-pc/core.img
update-grub

The first part installs grub to the boot position, even though it doesn’t like it, and the second forces the core file to be unchangeable… I’m not exactly sure of the impact of this, but it’s the only way to do the next part of this process. The last bit makes sure that you’ve got the latest grub config files installed.

Step 5: Reboot and test

Just check to make sure the machine boots OK!

You should have a booting Ubuntu derivative with an encrypted file system. Awesome.

Now let’s install Windows!

Step 6: Install Windows and Veracrypt.

You should boot from your install media, when you get to the partition selector, there should only be a single NTFS partition for it to use. Use it.

Install the latest version of Veracrypt from https://veracrypt.codeplex.com/

Once it’s installed, go to System, Encrypt System Partition/Drive, “Normal” system encryption, Windows System Partition, Multi-Boot (accept the warning), Boot Drive “Yes”, Single Disk, “Non-Windows Boot Loader” – No, and then… let it go through all the rest of the steps. There will be one stage where it asks you to create a rescue disk. Just save it for later. Once the encryption settings are collected, it will do a test (which is basically just rebooting to the boot loader, having you put in your password and going back into Windows), and then let it start performing the encryption.

Once the encryption finishes, reboot the computer, enter the decryption password and test it boots to Windows OK. Then reboot it again and press escape instead of putting in the password. It will boot to your Ubuntu system.

So, there you have it. One Dual-Boot system with encrypted disks everywhere!

Step 7: Setting up the shared volume.

After you’ve got the Ubuntu and Windows volumes sorted out, next we need the shared data volume to be organised. You’ll need Veracrypt for Ubuntu. Use the following to install the Veracrypt package for Ubuntu:

sudo add-apt-repository ppa:unit193/encryption
sudo apt-get update
sudo apt-get install veracrypt

Once that’s installed, boot back into Windows and create a new volume – perhaps V: for Veracrypt, or E: for Encrypted – your choice, but make sure you create it using the same password that you used for the Windows partition.

Format this new volume with either NTFS or FAT32 so that you can mount it under either operating system. I chose NTFS.

Now, you need to go into Veracrypt’s Settings menu, and select “System Encryption Settings”. Tick “Cache pre-boot authentication password in driver memory” (be aware, this means that if your machine is compromised when powered up, the password could be recovered), then OK. This may prompt you to accept the UAC at this point.

Next, with the mounted volume selected, go to the “Favorites” menu, and choose “Add to System Favorites”. In the screen which comes up, select the box under “Global Settings” which says “Mount system favorite volumes when Windows starts (in the initial phase of the startup procedure)”. There will be a warning about passwords that appears. Click OK.

You may, at this point, want to move certain aspects of your Windows desktop (e.g. the “My Documents” location) to the new mounted drive.

On the Linux OS, become root, with sudo, and then add the following lines to your crontab:

@reboot mkdir -p /shared_storage 
@reboot veracrypt --text --non-interactive --fs-options=uid=1000,gid=1000,umask=0077 --password="YOURSUPERSECUREPASSWORD" /dev/sda4 /shared_storage

These assume that your login user’s ID is 1000 (you can check that by running the command “id” as your logged in user), that you want to use “/shared_storage” as the mount point (it stops Ubuntu treating it as a “Mountable Volume” if it’s not in your home directory and not in /mnt or /media). These options also mean that only that user (and root) can access any of the files in that partition (although, it is only you on this laptop… right?), which means you can safely use it for any files which check user permissions before allowing you to access them (e.g. SSH keys). I then set up a symbolic link to /home/MYUSERACCOUNT/Documents into the /shared_storage/Documents directory, and /home/MYUSERACCOUNT/.ssh into the /shared_storage/SSH_Keys directory.

Citataions

The following list of resources helped me out when I was struggling with what to do next! They may not be canonical sources, but they helped.

  1. http://thesimplecomputer.info/full-disk-encryption-with-ubuntu – This is what got me started on this little journey!
  2. http://askubuntu.com/questions/161689/how-do-i-get-grub2-to-boot-a-truecrypt-encrypted-mbr – How to add the Veracrypt recovery disk to your Grub boot partition. Note, I do it slightly differently to this now.
  3. http://askubuntu.com/questions/711801/i-deleted-files-in-boot-now-cant-boot-linux – I may have done this. It tells you how to put all your important files back for booting purposes :)
  4. https://www.youtube.com/watch?v=Z1yWbBIqh1o – Walk through of installing Veracrypt to Windows 10. I used this to see some of the terms after I’d already installed Veracrypt. I don’t quite follow the same route as him though.
  5. https://www.linux.com/blog/how-full-encrypt-your-linux-system-lvm-luks – Using LVM inside Luks for the full-Linux disk (this was why I’ve re-written this post)
  6. https://wiki.archlinux.org/index.php/Dm-crypt/Encrypting_an_entire_system – Some details around how the Luks stuff all works

I may or may not have reinstalled Windows and Kubuntu about 20 times during this process, cursing myself for starting the whole damn process off in the first place!!!