# 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:

```bash
ss -tulpen
```

Flags:

- `-t` → TCP
- `-u` → UDP
- `-l` → nur listening sockets
- `-p` → Prozess anzeigen
- `-e` → erweiterte Infos
- `-n` → keine DNS-Auflösung (schneller)