It's important that you are running a supported version of GNU/Linux for security updates, and that you update frequently.
You should also have a good password, not something that is easily guessable. Even if you live alone and are the only one that has access to your computer.
I also strongly recommend that you are running a firewall. Ufw is a simple firewall for Linux and the one that I use.

The firewall setup below will work for most of your applications.
The ports listed are for my Debian install running Evolution as an email client.
If something breaks search for the firewall ports to open for the specific application.
Ufw is pretty popular and should be in your distributions repository.

To set up ufw run the following.

sudo ufw default deny incoming
sudo ufw default deny outgoing
sudo ufw allow out 53,67,68,123,137,465,993,995/udp
sudo ufw allow out 53,80,443,465,993,995,8880/tcp
sudo ufw disable && sudo ufw enable

Nov 19, 2023 by glenn.