You don't need a firewall on the LAN. It is just an annoyance to have to open ports later. Extra bureaucracy without benefits. This isn't Windows, you can can easily control your processes, choose if they bind to the network interface and on which port.
You shouldn't be touching it, honestly. There's a firewall at your router. It should be responsible for blocking incoming traffic. Firewalls on individual machines are for servers where you know exactly what's going in and out. I don't have a firewall on my desktop or laptop.
You will spend the best years of your life chasing random network connections if you block everything by default.
From Wikipedia, the free encyclopedia
Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).
Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.
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