On a default Trisquel installation there are very few open listening ports if
I remember correctly.
*sudo netstat -tulpn | grep LISTEN* will give you the info on which ports are
**open and listening** to the netz. You can quietly ignore those listening on
the localhost (127.0.0.1) for those are not visible externally.
> A firewall is not needed in Linux
True, when and if there are no open listening ports (Ubuntu by default).
An excellent practice IMHO is to purge any and every service you don't need.
For example, if you don't have a printer do you really need cups?
Mind that we are very precise with some words here - we call linux the kernel
and GNUx the OS.
Btw, welcome!
