Linux

Flatpak
Flatpak is a software package system for Linux, which is supported by a wide variousity of distributions and provide features like isolated environments (so called sandboxes) or creating your own repository for your applications. Flatpak is mainly used for graphical applications. 

 Concepts 

 Runtime - Applications do not run directly in your OS, they are isolated in Sandboxes. For each application, a so called runtime is chosen. Those runtimes are a base, which can be used by multiple applications. This base contains dependencies, libraries and other requirements the app needs to be executed. 

 Sandbox 

 Repository 

 Build a Flatpak bundle 

 TODO

Check open ports
If you want to check open ports on your Linux device, you can use the ss command (socket statistics). Older versions may use netstat . 

 ss 

 Example: 

 ss -tulpen 

 Flags: 

 

 -t → TCP 

 -u → UDP 

 -l → nur listening sockets 

 -p → Prozess anzeigen 

 -e → erweiterte Infos 

 -n → keine DNS-Auflösung (schneller)