Here is a stoopid question - no sign of Av or firewall that I can find?
Not stupid, just Windows habituated
Linux has very little malware so running AV software isn't a necessity to survive. ClamAV is in the software repositories & the likes of AntiVir & AVG do Linux versions - generally run as "on demand" scanners & not running all the time as for Windows.
If you're behind a router then that will generally provide enough basic firewall functionality. Gufw & Firestarter are a couple graphical firewall config tools if you want to run one.