UFW / GUFW /IPTables / netfilter

[Glennbo]

I guess a software firewall isn't needed in Linux, otherwise they would have one enabled upon installation, like Windows does.

[Snap]

That doesn't depend on the OS you're are using. The question is do I want to use a firewall (whatever your OS is)?

Some Linux distros have a firewall configured and ready to go, usually those having a desktop environment. Some others, usually small or barebones distros, leave to the user de decission of installing and setting one up.

ufw and gufw are just frontends for iptables. Really popular and easy to use. Nevertheless, besides many users still use iptables it's recommended to use nftables instead.

https://en.wikipedia.org/wiki/Nftables

https://wiki.archlinux.org/index.php/Nftables

[Glennbo]

I appreciate the info and links. I decided that I DO want a firewall (even though none was enabled by default), and just spent the last five hours trying to get my MythTV server accessible from my DAW and other machines on the network. I used ufw since it was natively installed, but not enabled, and after chasing down far too many ports for things like MySQL, and MAC addresses for hardware ethernet tuners, I finally have it all working like it was before enabling the firewall on all my recently converted Linux machines.

I may sometime in the future have a look at Nftables, but for now I at least have a functioning software firewall on all Linux machines. I'm guessing that just enabling it, is as good or better than Windows firewall, coz it sure broke a lot of connections just on my local network. Thanks again for your help.

[Snap]

You won't go wrong with iptables. It's only that nftables is a simpler, cleaner and better implementation. iptables works just fine. That's why a lot of users still use it. iptables vs nftables is more or less the same sort of scenario as vim vs neovim, mutt vs neomutt, etc... Just chose your poison.

[SmajjL]

So, if I did not install GUFW myself and activated it then Linux kernel by itself have firewall stuff built-in and blocks all by default?
Using iptables or what ever just is a way to speak/control the kernels fw?
I think I would prefer to use what ever my distro of choice's default is.
Thank you for the information! I am ready to understand this now and remove GUFW.

[Glennbo]

Originally Posted by SmajjL

So, if I did not install GUFW myself and activated it then Linux kernel by itself have firewall stuff built-in and blocks all by default?
Using iptables or what ever just is a way to speak/control the kernels fw?
I think I would prefer to use what ever my distro of choice's default is.
Thank you for the information! I am ready to understand this now and remove GUFW.

I found that no firewall was active or enabled until I enabled it with this command.

sudo ufw enable

Before doing that, I could access my MythTV server from my DAW, both of which are running Xubuntu. After enabling it, I could NOT access the Myth machine until I set rules for about six ports, and two hardware MAC addresses.

I don't know if your particular distro has any firewall enabled by default, but mine didn't.

[Snap]

Originally Posted by SmajjL

So, if I did not install GUFW myself and activated it then Linux kernel by itself have firewall stuff built-in and blocks all by default?

It depends on the distros. It's commonly disabled as default even if tools are already installed, usually left as an user choice to enable it.

Though I never done it myself, different sets of rules/configs can be switched depending on what you want to do at a given time. This involves dealing with services, but as usual, convenience/commodity/easy-going and best practices don't hold together.

Using iptables or what ever just is a way to speak/control the kernels fw?

Correct.

FWIW: Differences between iptables and nftables explained

https://linux-audit.com/differences-...les-explained/

Firewall for the lazy:

https://forums.bunsenlabs.org/viewtopic.php?id=1765