Category Archives: Development

Using Apache HTTP as reverse proxy

Using Apache HTTP as reverse proxy

The Apache HTTP Server, colloquially called Apache, is a free and open-source cross-platform web server. This article explains briefly how to set up Apache as a reverse proxy to a web site in an internal network.

To set the expectations in this article. I'm not going to explain you how to install Apache web server or how to get it operational on your system. There are thousands of tutorials including my own Accessing your web server via IPv6 on the Internet that already cover that step.

In case more information about the configuration directives used below is needed, I recommend to consult the official documentation of a particular keyword.

The scenario

I have a web site running on a system in an internal network. This could be either a full-fledged Windows/Linux server or an IoT device running on a single board computer (SBC), like i.e. a Raspberry Pi, an Arduino, ESP8266 chipset.

Using Apache HTTP as reverse proxy
A reverse proxy taking requests from the Internet and forwarding them to servers in an internal network. Source: Wikipedia

Now, I want to enable access from the Internet to that internal server using Apache.

Configuring Apache as reverse proxy

In order to complete our task we need to look into the features of the mod_proxy module for Apache. Here, we get a directive called ProxyPass which does the job as expected. According to Apache's Reverse Proxy Guide the simplest example proxies all requests ("/") to a single backend:

ProxyPass "/"  "http://www.example.com/"

Additionally, to hide any reference to the system on the internal network it is required to specify the directive ProxyPassReverse to modify certain HTTP header values in the response, and use the proxy data instead.

Following is a working example of how to set up a virtual host in Apache that provides reverse proxy capabilities.

<VirtualHost *:80>
        ServerName mediacentre.kirstaetter.name

        ProxyRequests On
        ProxyPreserveHost On
        ProxyVia full

        <Proxy *>
                Order deny,allow
                Allow from all
        </Proxy>

        ProxyPass               /       http://10.0.240.4:8080/
        ProxyPassReverse        /       http://10.0.240.4:8080/
</VirtualHost>

The host system on IP address 10.0.240.4 is part of an OpenVPN infrastructure and therefore accessible from the proxy system.

Multiple proxies possible

No problem with Apache. You can configure and run as many reverse proxies as would like to. One has to pay attention to avoid overlaps either via ServerName directive or by using different port numbers to bind to. Although I have only one reverse proxy running on Apache I configured multiple scenarios using nginx. More details are described in Using nginx as reverse proxy.

Do you have any interesting use cases or active configurations of Apache as reverse proxy? If yes, please use the comment section below give me and other readers more details. Thanks!

Image credit: Nick Fewing

Using nginx as reverse proxy

Using nginx as reverse proxy

Nginx (read: engine-x) has versatile options to set up web sites and more advanced configurations. This article explains briefly how to set up nginx as a reverse proxy to a web site in an internal network.

NGINX is a free, open-source, high-performance HTTP server and reverse proxy, as well as an IMAP/POP3 proxy server. Source: https://www.nginx.com/resources/wiki/

The scenario

I have a web site running on a system in an internal network. This could be either a full-fledged Windows/Linux server or an IoT device running on a single board computer (SBC), like i.e. a Raspberry Pi, an Arduino, ESP8266 chipset.

Using nginx as reverse proxy
A reverse proxy taking requests from the Internet and forwarding them to servers in an internal network. Source: Wikipedia

Now, I want to enable access from the Internet to that internal server using nginx.

Setting up nginx

In order to set up the solution you need to have a public facing web server on the Internet. Most probably it already runs nginx to serve your web site or blogging software.

I'm running a root server on Debian/GNU Linux and nginx is already installed. You can check your own system quickly like so for any running process:

$ ps fax | grep nginx

Or if you prefer a bit more details like so:

$ sudo service nginx status
● nginx.service - A high performance web server and a reverse proxy server
   Loaded: loaded (/lib/systemd/system/nginx.service; enabled)
   Active: active (running) since Do 2019-01-03 03:28:11 CET; 4 days ago
     Docs: man:nginx(8)
  Process: 29505 ExecStop=/sbin/start-stop-daemon --quiet --stop --retry QUIT/5 --pidfile /run/nginx.pid (code=exited, status=0/SUCCESS)
  Process: 29537 ExecStart=/usr/sbin/nginx -g daemon on; master_process on; (code=exited, status=0/SUCCESS)
  Process: 29535 ExecStartPre=/usr/sbin/nginx -t -q -g daemon on; master_process on; (code=exited, status=0/SUCCESS)
 Main PID: 29539 (nginx)
   CGroup: /system.slice/nginx.service
           ├─29539 nginx: master process /usr/sbin/nginx -g daemon on; master_process on;
           ├─29540 nginx: worker process
           ├─29541 nginx: worker process
           ├─29542 nginx: worker process
           └─29543 nginx: worker process

In case that nginx is not even installed on your system you could look up the package information like so:

$ apt search ^nginx

And install the web server using apt-get like so:

$ sudo apt-get install nginx-full

Which will then install nginx web/proxy server and all its dependencies on your server.

Configuring nginx as reverse proxy

Now, we have an operational installation of nginx on our Internet-facing system. We are going to create a new configuration file that defines the necessary proxy information to access our service on the internal network.

First create a new file below nginx configuration folder using your preferred text editor.

$ cd /etc/nginx/sites-available/
$ sudo nano raspberry

The file name should be relevant to either the kind of services or the system that you are going to shield using nginx as proxy.

Next, write the following server definition into your configuration file. Of course, you would adjust the server name and the IP address according to your environment:

server {
    listen 80;
    listen [::]:80;
    
    server_name raspberry.kirstaetter.name;
    server_tokens off;

    location / {
        proxy_set_header X-Real-IP $remote_addr;
        proxy_pass 10.0.240.3;
    }
}

That is the minimal configuration you would have to specify in order to run nginx as a reverse proxy to a system on your internal network. The given IP address needs to be accessible from your public web server, i.e. using a VPN infrastructure based on OpenVPN.

After saving and closing the new nginx configuration it is time to enable and check the syntax for any errors. To enable an available configuration you need to either place it or link it into the folder sites-enabled of nginx.

$ cd ../sites-enabled
$ sudo ln -s /etc/nginx/sites-available/raspberry raspberry

Now, to avoid any unexpected shutdowns or better said launching issues you should always run a configuration test before restarting the nginx service. This can be done quickly using the following command:

$ sudo service nginx configtest
[ ok ] Testing nginx configuration:.

Should your configuration file have any unknown directives and errors the output of configtest looks like this:

$ sudo service nginx configtest
[FAIL] Testing nginx configuration: failed!

You will find more details about the nature of the problem and the line number in the error log file below /var/log, i.e. here:

$ sudo cat /var/log/nginx/error.log
2019/01/07 13:50:07 [emerg] 21662#21662: unknown directive "server_?name" in /etc/nginx/sites-enabled/raspberry:5

Only when all problems have been resolved and you have a positive response from the configtest you should restart the nginx service.

$ sudo service nginx restart

Resolve a domain name

The above described sample is very basic, and sometimes it might be necessary to avoid using an IP address for internal service. Luckily, this can configured using the resolver directive in an nginx configuration file like so:

server {
    listen 80;
    listen [::]:80;
    
    server_name raspberry.kirstaetter.name;
    server_tokens off;

    resolver 127.0.0.1;
    
    location / {
        proxy_set_header X-Real-IP $remote_addr;
        proxy_pass rasp01.local;
    }
}

The change in our configuration file now assumes that I have a DNS server running on the local machine which knows how to handle and resolve the specified domain name rasp01.local.

Again, this article covers the basics of reverse proxying using nginx only. There are more interesting scenario like setting your own DNS server on the internal network to provide public access to an internal resource.

Perhaps, you might want to proxy an existing service with your own custom domain, in case that the service provide does not offer this option. Using a public DNS server like Cloudflare's 1.1.1.1, Google Public DNS (8.8.8.8), or OpenDNS as resolver should give you some ideas.

Provide secure access using SSL

Let's take the following scenario into consideration. Your internal resource might not be configurable with an SSL certificate but you would like to enable HTTPS protocol communication from the Internet. Setting up nginx with an SSL certificate is well-documented and to combine this with the above described proxy features is a breeze to achieve.

Following you will get a more complete configuration file based on the previous example, now SSL-enabled using a Let's Encrypt certificate.

server {
    listen 80;
    listen [::]:80;
    listen 443 ssl http2;
    listen [::]:443 ssl http2;

    server_name raspberry.kirstaetter.name;
    server_tokens off;
    server_name_in_redirect off;

    client_max_body_size 50m;

    ssl on;
    ssl_certificate         /etc/letsencrypt/live/raspberry.kirstaetter.name/fullchain.pem;
    ssl_certificate_key     /etc/letsencrypt/live/raspberry.kirstaetter.name/privkey.pem;

    # modern configuration. tweak to your needs.
    ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
    ssl_ciphers 'ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256';
    ssl_prefer_server_ciphers on;

    # HTTP headers
    add_header X-Content-Type-Options nosniff;
    add_header X-Frame-Options SAMEORIGIN;
    add_header X-XSS-Protection "1; mode=block";
    add_header Referrer-Policy no-referrer-when-downgrade;

    root /var/www/raspberry;
    access_log /var/log/nginx/raspberry.kirstaetter.name.access_log gzip;
    error_log /var/log/nginx/raspberry.kirstaetter.name.error_log info;

    resolver 127.0.0.1;
    
    location / {
        proxy_set_header X-Real-IP $remote_addr;
        proxy_pass rasp01.local;
    }

    location ~ /.well-known {
        allow all;
    }
}

The specified SSL options in regards to protocols and ciphers are an arbitrary choice of mine. If you have suggestions on how to improve the SSL setup, please leave a comment below.

Eventually the http2 directive might be an issue. Either check that you are using a recent version of nginx that has HTTP/2 support backed in or remove the value from the listen directive in the configuration file.

Multiple proxies

No problem with nginx. You can configure and run as many reverse proxies as would like to. Right now, I think I have three or four proxies running. Interestingly, one of them is an older set up based on Apache HTTPd which I'm going to write about in a separate article.

Do you have any interesting use cases or active configurations of nginx as reverse proxy? If yes, please use the comment section below give me and other readers more details. Thanks!

Image credit: Otto Norin

OpenVPN: All TAP-Windows adapters on this system are currently in use

OpenVPN: All TAP-Windows adapters on this system are currently in use

Working with several clients or partners might be an interesting challenge sometimes. While adding a new connection to an existing OpenVPN infrastructure I came across the following error message in the client log file: All TAP-Windows adapters on this system are currently in use.

Depending on how you actually installed your VPN client software you might be facing this issue while adding an additional client configuration for another connection. Especially when you are using a client software by a third-party provider, ie. WatchGuard Mobile VPN or Sophos. Perhaps you might be struggling to resolve it.

Get the TAP-Windows driver

Check whether you have the full installation of OpenVPN software. If yes, you might like to skip this the following steps and directly move on to add another TAP adapter to your Windows system.

Otherwise, please navigate to the Community Downloads of OpenVPN and either get the latest OpenVPN package, or if you think that this might be an issue, scroll down a little bit on same page and get Tap-windows package for your system. After the download is complete, run the installation routine and make sure to select TAP Virtual Ethernet Adapter like so:

OpenVPN: All TAP-Windows adapters on this system are currently in use

OpenVPN: All TAP-Windows adapters on this system are currently in use

You might have to reboot Windows to complete the network driver installation.

Add a new TAP virtual ethernet adapter

Now, you should be able to add an additional TAP interface to your system, and make it available for your new OpenVPN connection. Hit the Start button or press the Win key, then type tap and wait for Windows to give you its matches found on the system. Here is how it looks like on my Windows 10:

OpenVPN: All TAP-Windows adapters on this system are currently in use

Click on the entry Add a new TAP virtual ethernet adapter and confirm the User Account Control (UAC) dialog with Yes. You then see an administrative command prompt that adds another network interface to your Windows.

C:\WINDOWS\system32>rem Add a new TAP virtual ethernet adapter

C:\WINDOWS\system32>"C:\Program Files\TAP-Windows\bin\tapinstall.exe" install "C:\Program Files\TAP-Windows\driver\OemVista.inf" tap0901
Device node created. Install is complete when drivers are installed...
Updating drivers for tap0901 from C:\Program Files\TAP-Windows\driver\OemVista.inf.
Drivers installed successfully.

C:\WINDOWS\system32>pause
Press any key to continue . . .

And your OpenVPN client is ready to roll.

The shortcut below the Windows Start menu is linked to a batch file which you can also access and launch directly from %ProgramFiles%\TAP-Windows\bin

OpenVPN: All TAP-Windows adapters on this system are currently in use

Note: Ensure to run the batch file with administrative permissions. Otherwise, the driver installation will fail.

Review your existing Network Connections

Perhaps you would like to inspect the existing TAP-Windows Adapters? You find them in the Control Panel under Network Connections.

OpenVPN: All TAP-Windows adapters on this system are currently in use

The adapters are classified as TAP-Windows Adapter V9. Here you can enable, disable or even delete an existing network interface.

Some readers might prefer interaction with a command line interface (CLI). Well, even on Windows there is nothing to worry about this. The Network Shell (Netsh) of Windows has you covered, although it is recommended to use PowerShell to manage networking technologies:

PS C:\> Get-NetAdapter

Name                      InterfaceDescription                    ifIndex Status       
----                      --------------------                    ------- ------       
vEthernet (Default Swi... Hyper-V Virtual Ethernet Adapter             30 Up           
Wi-Fi                     Killer Wireless-n/a/ac 1535 Wireless...      28 Up           
Ethernet                  Killer E2500 Gigabit Ethernet Contro...      19 Disconnected 
Ethernet 4                TAP-Windows Adapter V9 #2                    15 Disconnected 
VMware Network Adapte...8 VMware Virtual Ethernet Adapter for ...      14 Up           
VMware Network Adapte...1 VMware Virtual Ethernet Adapter for ...      13 Up           
Ethernet 2                ThinkPad USB-C Dock Ethernet                  8 Disconnected 
Ethernet 5                TAP-Windows Adapter V9 #3                    52 Up           
VirtualBox Host-Only ...2 VirtualBox Host-Only Ethernet Adap...#2       6 Up           
Ethernet 3                TAP-Windows Adapter V9                        5 Up           

The information provided is identical to the visual representation in Windows Explorer.

ICT skills at primary school

ICT skills at primary school

Our children have computer lectures at their primary school since this year. In general, it's a great idea that students are exposed to computer literacy at an early stage. But sometimes it comes with small hiccups. Like in our case...

Curriculum, literature and exercise book

Although our children have access to computers at home since a while already it is the curriculum of their primary school in regards to IT literacy that lead to this blog article.

The title "Let's Learn ICT Skills" by the Mauritius Institute of Education (MIE) introduces Computer Fundamentals and Operations to young learners at primary school level. The textbook is divided into six units and covers first steps into the world of ICT.

Starting with an orientation in Windows the title discusses the essential use of typical desktop applications to handle word processing, to introduce simple graphics and presentation skills, to cover basic functionality in spreadsheets and to venture into the unknown areas of the interweb.

Each chapter has different learning objectives and introduces elementary skills in various applications. To keep matters easy the textbook is focused on Windows operating system and the Microsoft Office suite. Which in general and most commonly okay for the majority of primary school students.
Not sure whether it classifies as a tutorial. You are most welcome to comment and assist. #BlogMore about modern parenting obstacles...

https://jochen.kirstaetter.name/azure-for-school/
Well, most students... ;-)

Our start situation - Linux

As a parent it is not easy to trust a full-fledged computer into the hands of your youngster(s) without fearing the whole system might be infested by viruses, malware and ransomware in shortest time. Especially given recent reports on various problems.

Following my decision to provide our kids with family-friendly and security-enhanced tablets running on Amazon's Fire OS compared to regular Android, it was only right to provide them a similar experience on the desktop. At least in my point of view.

Personally, it was important for me to have peace of mind knowing our children are using Linux based system. Don't get me wrong Microsoft has done a tremendous job to improve security over the last decade. It's just that I didn't want to purchase a new laptop for them and Linux runs just fine on older hardware.

Instead of upgrading the available HP laptop from Windows Vista Business to latest Windows 10 I decided to install Xubuntu 17.04 originally. Some weeks back, I then upgraded their machine to Bionic Beaver (version 18.04) already, and they can "beta-test" the upcoming Ubuntu LTS version.

After all, as more and more software is moved towards web applications it really doesn't matter anymore whether Firefox is run under Windows or Linux, does it? Additionally, they have access to LibreOffice, GIMP and other educational software packages like GCompris, and so forth.

Well, the children's exercise book is explicitly covering Windows, some applications of the Microsoft Office suite as well as Paint.net - software that isn't available on Linux out of the box.

Various approaches possible

Of course, there is no golden solution to this situation and multiple possibilities are given. All depending on circumstances, personal taste and eventual hardware constraints. Following, I would like to give you an overview of options - all of which I already used successfully in the past.

Virtualisation

This might come first in someone's mind and I have to agree with that. Installing a virtualisation software like Oracle VirtualBox, VMware Workstation or even qemu can be done easily and the the actual experience can be seamless. In our situation though is the existing hardware with a previous generation CPU and 2 GB RAM only the limiting factor to this approach.

Using wine or CodeWeavers CrossOver

Emulation software like wine or CodeWeavers CrossOver eliminate the necessity to install and run a complete virtualisation solution. The software provides an abstraction layer of native Windows API functionality and allows to install and run Windows software like the Microsoft Office suite among others directly on a Linux machine. Luckily, the hardware wouldn't be the limiting factor but I have to confess that it is my laziness to opt-in for this viable approach. Also, the first chapter in the kids' literature - Getting familiar with Windows - wouldn't be possible for them using this approach.

Remote access

Last but not least, providing remote access to an existing instance of a Windows system seems to be one of the easiest options. Here, the kids get to experience Windows directly and it doesn't need any resources on their Linux system. Using a software package like rdesktop or remmina enables a Linux user to connect to a Windows system via Remote Desktop Protocol (RDP). So far so good, but I'm not interested to provision a dedicated machine for this purpose at home. The system would be idle most of the time and consume a good chunk of electricity instead.

As mentioned earlier I have used all those approaches successfully, and it is good fun to tinker around with them. But those are most likely options for an adult and not really suitable for a child attending primary school.

A solution - Cloud-based virtual machine

Taking the pro aspects of each of the approaches earlier I decided to provision a virtual machine running Windows 10 Professional in the cloud. Access to that machine is available using RDP and in regards to hardware constraints it requires an internet connection only.

Actually, this suits me very well as it gives me control on various levels:

  • Local network: I can control at any time whether the kids' laptop gets access to our WiFi network or the internet based on simple authentication and routing configuration.
  • Operating times: A virtual machine in Azure is fully controlled through the Azure portal. I can decide when the VM is running and when not.
  • Hardware on demand: Provisioning hardware to the VM on Azure is just a few clicks and a reboot away.
  • Data exchange: Synchronisation of files between the local Linux laptop and the Windows machine in Azure is based on cloud storage providers like OneDrive, Google Drive, Dropbox, etc. Meaning backup of files is integrated and additional devices like their tablets can be added easily.

Later on, if the VM isn't needed anymore or in case the children totally messed it up I don't have to worry about anything. The VM gets decommissioned and can be provisioned again within minutes if needed.

Azure configuration and fine-tuning

To start with this educational system for my children I went into the Azure Portal and created a new virtual machine using the Windows 10 Pro image. To keep nice and smooth I also created a new resource group to isolate it from other business-related activities.Given

Size of the VM

ICT skills at primary school
I chose a (hopefully) decent hardware setup running the virtual machine on a Standard B4MS (4 cores with 16 GB RAM) tier. This should be sufficient enough for Microsoft Office, Paint.net and Firefox.

Auto-shutdown

Also, I activated the Auto-shutdown feature which restricts the use of the system until a specified time, and helps me to save a heap of money, too.
ICT skills at primary school
The main purpose of that VM is to allow the children to follow the exercises and steps in their school book. At the given time the system simply shuts down, and it's dinner time in the off-line world.

Starting the VM

Now that we know how to stop the VM we should have a look about how to start it. There are multiple choices available. Most obvious you can launch the virtual machine via the Azure Portal itself. Nothing surprising here.

Next, Microsoft offers the free Azure mobile app for Android and iOS to stay connected to your Azure resources. This is quite neat to manage, monitor and operate Azure on the go.

And then there is azure-cli - the Command-line tools for Azure - which gives you the next generation multi-platform command line experience for Azure.

$ az 

     /\
    /  \    _____   _ _  ___ _
   / /\ \  |_  / | | | \'__/ _\
  / ____ \  / /| |_| | | |  __/
 /_/    \_\/___|\__,_|_|  \___|


Welcome to the cool new Azure CLI!

Usually, I have Visual Studio Code open almost the whole day and starting the kids' virtual machine is done using the Azure CLI Tools extension.
ICT skills at primary school

I'm currently using the following .azcli file to manage that VM:

# Logging into Azure
az login

# Starting kids' VM on Azure
az vm start -g Personal -n windows4kids

# Stopping kids' VM
az vm stop -g Personal -n windows4kids --no-wait

The az login triggers the device login on Azure and after entering a generated code to authenticate your machine you get access to your resources on Azure, like this:
ICT skills at primary school

Accessing the VM

Windows machines on Azure are accessed via RDP and Linux has a variety of client applications for that protocol. In the portal you should assign a static domain name to your VM as the public IP address is most likely to change between daily uses. The portal allows you to download the Connect parameters as a .rdp file that you can open in any text editor on Linux.

ICT skills at primary school
Using the details from the .rdp it is possible to set up a new connection in remmina for future use. I'm storing the password to keep it simple for the children to access their new Windows machine.

Now, remmina is configured to start automatically after they logged into their account and the Windows VM on Azure is easy accessible via shortcut from the system tray area.

Give it a try - Azure free credit

Microsoft gives new sign-ups on Azure an initial credit that allows you to explore the various options and get yourself familiar with the available resources. Why don't you give it a try?

Ghost Desktop on Xubuntu 17.04 won’t start

Ghost Desktop on Xubuntu 17.04 won't start

Already before the migration from Joomla to Ghost last weekend I run the Ghost Desktop application on Windows. Now, after the successful completion it was about time to get going on my other machines. You know, the ones away from the main rig... Usually used during the evening hours, just for fun, or experimenting.

Tonight, I decided to give one of my Linux systems some attention, started to upgrade some packages, and installed new software. Among those also Ghost Desktop App for Linux. On the Ghost website you get version 1.3.0 (as of writing), and it's a Debian package.

Knowing that the desktop app is an Electron-based application, and I already packaged a few Electron apps myself, it would run on any Ubuntu-based system, too.
Note: This post was written in Ghost Desktop running on Xubuntu 17.04 64bit

Installation of Ghost Desktop

Either you double-click on the downloaded .deb package and your system will prompt you to open/install the application in Software, or you can run the following command in the Terminal:

$ sudo dpkg -i ~/Downloads/ghost-desktop-1.3.0-debian.deb 

Ghost Desktop can then be launched via the Application Menu/Launcher under ghost-desktop or if you prefer the terminal:

$ Ghost

The problem: Ghost Desktop won't start

If you try to launch the application via the menu or any other GUI launcher you won't get any response at all. The software just isn't executed, it seems.

Compared to running it in the Terminal. This might produce the following output:

$ Ghost
A JavaScript error occurred in the main process
Uncaught Exception:
Error: Unable to find a valid app
    at Object.<anonymous> (/usr/lib/Ghost/resources/electron.asar/browser/init.js:121:9)
    at Object.<anonymous> (/usr/lib/Ghost/resources/electron.asar/browser/init.js:173:3)
    at Module._compile (module.js:571:32)
    at Object.Module._extensions..js (module.js:580:10)
    at Module.load (module.js:488:32)
    at tryModuleLoad (module.js:447:12)
    at Function.Module._load (module.js:439:3)
    at Module.runMain (module.js:605:10)
    at run (bootstrap_node.js:424:7)
    at startup (bootstrap_node.js:147:9)

The solution: Set permissions

Fortunately, this has been reported already on GitHub by user letsjustfixit. The issue is caused by a missing permission bit on the Electron app. A temporary workaround has been documented until the package is going to be fixed.

Run the following chmod to set read and execute bits on the Electron app and dependent components. Then launch Ghost Desktop again.

$ sudo chmod -R +rx /usr/lib/Ghost/resources/app
$ Ghost 

 ⚡️  Welcome to Ghost  👻

Happy blogging!

It's great to see that such issues are handled on GitHub, and the "fix" is easily done.

As maintainer of own Electron-based applications I'm interested in the root cause. So far, I didn't come across a similar problem (touching wood!). Thankfully, I'm going to add this to my notes on Electron.

If you're familiar with this kind of problem regarding Electron packaging on Linux, give it try to fix it. On my side, I already cloned the Ghost-Desktop repository. Let's see whether I'm able to create a pull request for the Ghost community.