"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.

My Fujitsu Stylistic V727

Review of my Fujitsu Stylistic V727 Laptop/Tablet.

TL;DR: Linux is usually awesome, but it doesn’t work for my niche case.

Why was I in the market for a new computer?

October 2019 my beloved (but 7 year old) Acer V5-171, “Minilith” (so named because it was smaller than it’s predecessor, a 17″ monster of a black slab that was named “Monolith”) started exhibiting signs of having a dead battery. I replaced the battery with an 3rd party replacement, and while it charged OK for a few runs, it stopped charging all together (I could get a maximum of 5% charge), so I put the old battery in, and it started working better. Huzzah. All was going well until around 6 months ago when the hard drive failed, so I replaced it with an SSD, and that gave it a new lease of life… and this month, well, it just wouldn’t boot reliably. I finally decided that it was time to let it go and play with Timmy the dog at the farm, and replace it with something newer.

The back of "Minilith", my 7 year old Laptop.
The back of “Minilith”, my 7 year old Laptop.
Minilith's Keyboard and Screen
Minilith’s Keyboard and Screen

Fortunately, this co-incided with a small win on the company social Prize Draw of a reasonable sized pay out, enough to consider looking at the Ex-Demo staff sales list made available to me by dint of my employer.

Making my choice.

There weren’t a lot of options, to be fair, but one item stood out to me. A Stylistic Tablet Computer. I’d previously had an Asus Transformer TF300T – a tablet-come-computer which had a detachable keyboard. I’d loved that, even though it didn’t really do what I wanted it for (and, I think I’d paid quite a bit over what it was worth, really)… but what I really wanted to do was have a tablet I could use for computing… Hence, the Stylistic.

Image of the TF300T, a tablet model I’d previously owned, from the Asus Transformer Marketing Pages
Der obere Teil des Stylistic V727 ist ein Tablet.
Image of the tablet view of the Stylistic V727 computer from a German blog.

Fujitsu are in a bit of an odd place, at least in the UK (I’ve not looked elsewhere) for personal computers – we sell quite well (apparently) to business, but we moved out of the “selling to the public” market probably around 2010, and so it was pretty hard to gauge how well this laptop performed. Oh, and of course, being a “Linux Enthusiast”, I wanted to be able to run Ubuntu, Fedora or others on it.

Because it was an internal sale, and I wanted to test Ubuntu on it before I bought it, I was able to get the sales team to let me evaluate it before I bought it.

It arrives!

It arrived as the tablet and keyboard, with a dock for setting it on your desk. I tested it with Windows, where the dock worked well, but the keyboard by itself didn’t so much. You see, the keyboard is an optional accessory, and had been sold with the laptop, all good thus far. Except what you also need to get, when you get the keyboard, is the case. The case gives you the sturdy back to give the “laptop” a frame. It’s basically the hinge that the top-heavy screen needs to keep itself upright.

A screen capture of the Fujitsu Stylistic V727 from the datasheet. Note this image shows the optional keyboard and the optional case.

The sales team were very understanding, and found a case to ship to me as well, but it wouldn’t come for a few days, so I was left to try out the rest of the hardware.

What do you get for your money?

The processor is an Intel i5-7Y57 dual core CPU with four threads, running at 1.2GHz.

It has 8GB of RAM and a 256GB m2 SATA drive.

The 12.3″ touch-or-pen (included) enabled screen has a maximum resolution of 1920×1280 pixels. The surface of the tablet is considered a WACOM tablet, and the pen can be sensed from a reasonable distance away. There are two buttons on the side of the pen, which turns a tap on the screen from a “normal” left click to a right click, or a center click.

On the rear is a fingerprint sensor.

From a network perspective, the WIFI supports 802.11ac, Bluetooth 4.2, and under the battery there is a LTE module onboard (although, I’ve not tested that).

On the side is a USB3.1 A connector, and a USB C connector (the specs sheet I linked to above suggests there is a single USB 3 and a USB 2 interface, but I doubt the USB C is USB 2).

There is also a MicroSD slot, which is detected by the booted OS as an MMC device, but it is not detected as a bootable device.

There’s a combined 3.5mm audio in and out jack, which I’ve not tried and a power socket.

There are two cameras, a 5 megapixel front-facing camera and an 8 megapixel rear facing camera with a flash.

The detachable keyboard has an integrated touchpad. It’s all good, and compared to my poor Acer V5, it’s a massive step up ❤

When you add in the desk dock (where, to be fair, it’s spent most of it’s time since I got it), the connections also then include Gigabit Ethernet, a Display Port interface, a VGA port and three USB 3 A interfaces, and a power socket.

The OS Comparison starts

Windows first

I booted it in Windows, and found it really rather responsive, especially once I’d reinstalled Windows without all the customizations the demo team had put on…

My previous install of Windows on Minilith had been the Home edition, and I’d found the semi-constant nagging to install games and the like rather annoying. I’ve had a couple of Windows 10 Professional installs at work, and, while those builds came with their own fair share of corporately mandated bloat (after all, their threat models are somewhat different to mine) they usually felt more slim than the Windows 10 home install I’d had, so when I saw this had Windows 10 Professional, I was looking forward to seeing something a bit leaner… and I wasn’t let down. All the hardware worked fine, I had the fingerprint reader working, no worries and the dock was great.

Docking and undocking is relatively seamless, although the first try was a bit tricky, I’ve got used to it. I had two screens attached via my work-supplied Fujitsu PR08 DisplayLink adaptor, plugged through the dock, and again, that all worked fine.

I could use the pen in the tablet mode really well. It makes selecting items on the screen easy, and if you don’t want to use the virtual keyboard, in some cases, it pops up a handwriting recognition box, although the time I showed this to my wife (where I’d been using it successfully for some time), it didn’t recognise half the words I wrote… but I’m sure that’s just my dreadful scrawl, and not the tablet’s fault!

Even using the tablet without the pen worked really well. Tapping the screen is a left click, and a long press on an area is a right click, similar to how Android handles left-and-right clicks in RDP and VNC sessions. The keyboard has several “modes” – a reduced character set, a thumb typing set or a full keyboard. The reduced set has a control key and an escape key, but no alt, windows or arrow keys. I didn’t try the thumb typing set (this thing is 12″ across!) but the full keyboard is an “ISO layout” 75% keyboard (I discovered by matching the image to this website!) which means I still get my Control, Alt, and Windows keys.

Next, Ubuntu

I booted from a USB stick that had the Ubuntu 20.04 installer on it. Ubuntu booted fine, allowed me to repartition the Windows partition into approximately half the drive, and install away. During the install, I was asked to provide a password to setup the SecureBoot keys, and instructed that it’d prompt me for it on the next reboot. Most of the hardware worked fine. Dock, keyboard, Wifi, Bluetooth… all good. The fingerprint sensor wasn’t detected, and still isn’t, but I’m OK with that, it was always just a nice-to-have. The install worked fine, and yes, on reboot, I got a blue screen asking me to set up my “MOK” (which, I guessed eventually, was the SecureBoot setup). I realised that the SecureBoot install stage of the Linux install copies a private key to the UEFI space, and on the next boot, it spots there’s a key there and asks you to unlock that private key, so it can install it into the boot keys. All good!

I was working away on it with the tablet in the dock. I tried using it with the detachable keyboard, but it was a bit tricky to use without the rigid back, so I kept it in the dock. The pen works a treat too.

The problem came when I tried to use it as a tablet.

You see, where Windows has a selection of keyboard layouts for their “On Screen Keyboard” (OSK), the Gnome one only lets you use this layout:

GNOME 3.28 OSK
Screenshot taken from an article at OMG Ubuntu.

While this is passable for tapping stuff into a URL bar in your browser, entering a password for logging in, or typing simple statements into dialogue boxes, there are some key things it’s missing. The first (for me) is a Control, Alt or Super (Windows) key. This means I can’t do any programming, of any sort, in Tablet mode. Note, this just works on Windows, and is possible on Android with an extended keyboard called “Hacker Keyboard”. There are also no cursor keys, which seems like it’s less important, but it makes editing things you’ve typed (or mistyped) MUCH harder.

“Well, OK then, let’s have a look around and see what our options are?”

I’d heard good things about “OnBoard”, a predecessor to Gnome OSK, but because OSK is registered as “The” on screen keyboard, and runs as a system process, and OnBoard is a user process, Gnome OSK pops up any time you want to do on screen keyboard things, even if you’ve got OnBoard loaded. Ahah! I found an extension which blocks Gnome OSK… except that stops it from being able to be used for logging in.

You see, that whole “system” versus “user” process thing I mentioned before. The Gnome lock screen is considered a system process, not a user one, which means that if you’ve disabled Gnome OSK, then you can’t put your password in, but equally, if you’re typing in a box with OnBoard, change focus and change back again, up pops Gnome OSK.

Breaking down and turning it around.

I should confess, I didn’t spend a lot of time wondering about this. I booted a Kubuntu environment instead, and found that this really didn’t work for me either (although I now don’t remember what stopped me from liking it – I might have to revisit this!) By this point, I’d spent several hours “messing” around with this, and I just wanted to give something a try. So I booted back into Windows.

I gave the on screen keyboard another try. It worked great. I tried doing some sketches in Paint 3D (the replacement for Windows Paint) with the pen, and it was very easy (so much so, I need to work out how to use it for my next design call with work!)

All the familiar tools I use in my work or personal environment are there.

  • VSCode. Check.
  • A usable shell (via Windows Subsystem for Linux). Check.
  • File synchronization (via Syncthing). Check.
  • Web browser (Firefox). Check.
  • Audio recording software (Audacity). Check.
  • Image editor (GIMP). Check.
  • Voice chat for the podcast software (Mumble). Check.
  • Screencasting software (OBS). Check.
  • Virtual Machine software (VirtualBox, Vagrant, Terraform). Check.

And the fingerprint reader works… so I stuck with Windows 10.

The only last catch, whether it was Windows or Linux? There’s no HDMI or VGA out without the dock… so I need to start looking into “cheap” display adaptors that I can use for presenting things, whenever we get back to “normal” and I can start attending and speaking at conferences again.

What about the case?

Oh yehr, so a few days after I get the computer, the case turns up. It attaches to the back of the computer with tape, and feels like leather (although, I’m sure it’s not leather). It definitely makes it feel like a “quality” product 😀. It’s a little bit more tricky to drop into the dock, but it makes it feel like a Laptop when you’re using it like one. The detachable keyboard is interesting. I’ve used it in the car, waiting for children to finish activities, and it’s fine, because it goes flat. I’ve detached the keyboard from the screen to just do tablet-y things with it, and that’s fine too.

So in summary

I think if I didn’t want it to be a tablet as much as a computer, I’d have been fine.

If you want a Windows Tablet that turns into a Laptop, it’s fine. If you want a low-profile desktop computer (in a dock) that can become a laptop, it’s fine.

But until Gnome or one of the other flavours gets a handle on how to do a reasonable on-screen keyboard… I don’t think I’ll be using Linux on here (because it’s also a tablet) for the next few months… and I think that’s going to be OK.

All of that said, if you use any Linux distributions with a tablet style mode, and you’ve got a working OSK, please contact me (via one of the links at the top of the site) to let me know what and how you did it, and I’ll give it a try too!

"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.