Security vulnerability with default setup

[Deams51]

The current setup guide for Linux (here) is unsafe.
It's not your role to take care of the server's security, but what do you think about adding a comment at the end about it?

After just a week, one of our servers got infected by the kinsing malware, a cryptocurrency miner.
The issue has been documented here

It could be avoided easily by for example setting up the firewall on the server to prevent access to the redis instance:

sudo ufw default deny incoming
sudo ufw default allow outgoing
sudo ufw allow ssh
sudo ufw allow 8080
sudo ufw allow 8081
sudo ufw allow 8008
sudo ufw enable

[bmartinn]

Thanks @Deams51 !
That is a great idea, and I think it relates to more than just the Linux install, I guess it would apply to any AMI/GCP image as well (i.e. firewall setup).

Maybe we should have a short document like "Securing your Trains-Server" with the suggested firewall configuration section, and maybe a link to the "Web login authentication" instructions etc.

What do you think?
Any chance you would start it with a quick PR?