Firewall on Linux is something I still don’t understand, and explanations found on Internet have always confused me. Do you happen to know some good tutorial to share? Or maybe one doesn’t need to do anything at all in distros like Ubuntu?
Thank you ALL for the great advice and guides! I’m writing from behind a laptop firewall now, and don’t notice anything :) It was smoother than I expected. In the end I used UFW because it was already installed, but I’ll take a look at firewalld too in some days! I don’t have any incoming ssh connections (not a server), so I didn’t need to worry about that :)
For example, if I open my settings (I’m on Ubuntu+KDE) I don’t see any firewall settings to configure. So I expect this is automatically done by the OS, but maybe I’m wrong. A bit surprised that the system itself doesn’t recommend using a firewall, to be honest.
Many firewall tutorials start speaking about “your server”. Then I wonder: is this really for me? I don’t have a server. Or do I?
I now see that the tutorial from @toikpi@feddit.uk gives a better explanation, cheers! So I see it’s good to have a firewall simply because one connects to public wifis from time to time.
I see that both UFW and firewalld are recommended… is it basically OK whichever I choose?
UFW is installed by default on Ubuntu. If it has been uninstalled for some reason, you can install it with sudo apt install ufw.
Using IPv6
sudo nano /etc/default/ufw
That command should come back with this
IPV6=yes
Save and close the file. Now, when UFW is enabled, it will be configured to write both IPv4 and IPv6 firewall rules. However, before enabling UFW, we will want to ensure that your firewall is configured to allow you to connect via SSH. Let’s start with setting the default policies.
These commands set the defaults to deny incoming and allow outgoing connections. These firewall defaults alone might suffice for a personal computer, but servers typically need to respond to incoming requests from outside users. We’ll look into that next.
To configure your server to allow incoming SSH connections, you can use this command:
sudo ufw allow ssh
This will create firewall rules that will allow all connections on port 22, which is the port that the SSH daemon listens on by default. UFW knows what port allow ssh means because it’s listed as a service in the /etc/services file.
However, we can actually write the equivalent rule by specifying the port instead of the service name. For example, this command works the same as the one above:
sudo ufw allow 22
If you configured your SSH daemon to use a different port, you will have to specify the appropriate port. For example, if your SSH server is listening on port 2222, you can use this command to allow connections on that port:
The main one everybody uses at least from my knowledge and from what I’ve used over the last 13 years is UFW. That is what you want to use.
I could easily say that for firewalld… 😃
Ufw is typically available/pre-installed with Debian based systems (Debian, Ubuntu, zzz), while Firewalld is typically available on Red Hat Enterprise Linux and derivates (Fedora, CentOS, Rocky, …)
I don’t think you need to configure your firewall.
Firewalls are usualy used to block incomming connectings. Usualy a Firewall that blocks all incomming connections is already active on your modem/router. Adding exception to the modem/router Firewall usualy happen through port forwords.
ebtables and iptables can be very complex. And I failed my 1st RHCE exam because of them. But once you learn, you will never unlearn, as they are quite beautifully crafted. You just need to get into the mindset of the people who wrote the tools…
Look into firewalld
It has a rather simplified cli interface: firewall-cmd
The manpages will tell you a lot.
firewall-cmd —add-service=ssh
Will open the ports for your ssh daemon until you reload your firewall or reboot your system
firewall-cmd —permanent —add-service=ssh
Will open the ssh ports until you remove them
firewall-cmd —list-all
Will show you the current firewall config
Thank you for the advice!
Firewall on Linux is something I still don’t understand, and explanations found on Internet have always confused me. Do you happen to know some good tutorial to share? Or maybe one doesn’t need to do anything at all in distros like Ubuntu?
Regarding ssh: you only mean incoming ssh, right?
@bushvin@pathfinder.social @toikpi@feddit.uk @hevov@discuss.tchncs.de @ChonkaLoo@lemmy.world @HotBoxghost2743@lemmy.ml @c1177johuk@lemmy.world (I’m surely forgetting someone, sorry)
Thank you ALL for the great advice and guides! I’m writing from behind a laptop firewall now, and don’t notice anything :) It was smoother than I expected. In the end I used UFW because it was already installed, but I’ll take a look at firewalld too in some days! I don’t have any incoming ssh connections (not a server), so I didn’t need to worry about that :)
Really great people here at Lemmy :)
You’re welcome friend!
What don’t you completely understand about Linux firewall? I don’t mind helping you learn
Thank you everyone, also @bushvin@pathfinder.social @toikpi@feddit.uk.
For example, if I open my settings (I’m on Ubuntu+KDE) I don’t see any firewall settings to configure. So I expect this is automatically done by the OS, but maybe I’m wrong. A bit surprised that the system itself doesn’t recommend using a firewall, to be honest.
Many firewall tutorials start speaking about “your server”. Then I wonder: is this really for me? I don’t have a server. Or do I?
I now see that the tutorial from @toikpi@feddit.uk gives a better explanation, cheers! So I see it’s good to have a firewall simply because one connects to public wifis from time to time.
I see that both UFW and firewalld are recommended… is it basically OK whichever I choose?
The main one everybody uses at least from my knowledge and from what I’ve used over the last 13 years is UFW. That is what you want to use.
A firewall is very important not just for being on public Wi-Fi connections. A firewall is your extra layer of protection
I don’t know what Distro you run. But it’s almost the same for each one
https://www.digitalocean.com/community/tutorials/how-to-set-up-a-firewall-with-ufw-on-ubuntu-20-04
UFW is installed by default on Ubuntu. If it has been uninstalled for some reason, you can install it with sudo apt install ufw.
Using IPv6
sudo nano /etc/default/ufw
That command should come back with this
IPV6=yes
Save and close the file. Now, when UFW is enabled, it will be configured to write both IPv4 and IPv6 firewall rules. However, before enabling UFW, we will want to ensure that your firewall is configured to allow you to connect via SSH. Let’s start with setting the default policies.
Setting up default policies
sudo ufw default deny incoming sudo ufw default allow outgoing
These commands set the defaults to deny incoming and allow outgoing connections. These firewall defaults alone might suffice for a personal computer, but servers typically need to respond to incoming requests from outside users. We’ll look into that next.
To configure your server to allow incoming SSH connections, you can use this command:
This will create firewall rules that will allow all connections on port 22, which is the port that the SSH daemon listens on by default. UFW knows what port allow ssh means because it’s listed as a service in the /etc/services file.
However, we can actually write the equivalent rule by specifying the port instead of the service name. For example, this command works the same as the one above:
If you configured your SSH daemon to use a different port, you will have to specify the appropriate port. For example, if your SSH server is listening on port 2222, you can use this command to allow connections on that port:
Then enable
sudo ufw enable
I could easily say that for firewalld… 😃
Ufw is typically available/pre-installed with Debian based systems (Debian, Ubuntu, zzz), while Firewalld is typically available on Red Hat Enterprise Linux and derivates (Fedora, CentOS, Rocky, …)
But it boils down to what you prefer, really.
I know all this already. But I also use arch and have been for the last 6+ years and I use ufw lol
Yes. Whichever works for you should be fine. In the end you should be able to manage it
Yes, usually you configure your endpoint firewall to block incoming traffic, while allowing all outgoing.
Unless you’re in a very secure zone, like DMZ’s.
I don’t think you need to configure your firewall. Firewalls are usualy used to block incomming connectings. Usualy a Firewall that blocks all incomming connections is already active on your modem/router. Adding exception to the modem/router Firewall usualy happen through port forwords.
Firewall - While this tutorial is Ubuntu 16.04 it should work current versions of Ubuntu https://www.linuxbabe.com/desktop-linux/getting-started-gufw-ubuntu-16-04 It should work for other distributions once you change the package manager.
ebtablesandiptablescan be very complex. And I failed my 1st RHCE exam because of them. But once you learn, you will never unlearn, as they are quite beautifully crafted. You just need to get into the mindset of the people who wrote the tools…Look into
firewalldIt has a rather simplified cli interface:firewall-cmdThe manpages will tell you a lot.
firewall-cmd —add-service=sshWill open the ports for your ssh daemon until you reload your firewall or reboot your systemfirewall-cmd —permanent —add-service=sshWill open the ssh ports until you remove themfirewall-cmd —list-allWill show you the current firewall config