Uncomplicated Firewall (UFW) on Arch Linux


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While migrating one of my VPS servers to Arch Linux I deployed Uncomplicated Firewall (UFW) to handle basic firewalling duties. I like ufw as it provides simple host-based firewall management and, in my opinion, one of the better projects to come out of the Ubuntu camp.

Install ufw as follows.

sudo pacman -Syy -noconfirm --needed ufw

Configuring ufw is simple but make sure you have console access to the host you are configuring just in case you lock yourself out.

NOTE! When enabling ufw the chains are flushed and connections may be dropped. You can add rules to the firewall before enabling it however, so if you are testing ufw on a remote machine it is recommended you perform...

ufw allow ssh/tcp

...before running sudo ufw enable. Once the firewall is enabled, adding and removing rules will not flush the firewall, although modifying an existing rule will.

Set the default behaviour to deny all incoming connections.

sudo ufw default deny

Open up TCP port 22 but with rate limiting enabled which will deny connections from an IP address that has attempted to initiate 6 or more connections in the last 30 seconds. Ideal for protecting sshd but you should conisder other SSH brute force defense techniques as well.

sudo ufw limit tcp/22

I'm hosting a few websites on my VPS so I open http and https.

sudo ufw allow 80/tcp
sudo ufw allow 443/tcp

Enable the ufw systemd unit.

sudo systemctl enable ufw
sudo systemctl start ufw

However, ufw is not enabled at this point. To enable the firewall you also have to do the following.

sudo ufw enable

You can see the status of the firewall using sudo ufw status.

On low-end servers it might be beneficial to disable logging.

sudo ufw logging off

At this point you should have a basic firewall configured and ufw help or the references below will assist you.

References
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