Started off by
- Enabling unattended updates
- Enable only ssh login with key
- Create user with sudo privileges
- Disable root login
- Enable ufw with necessary ports
- Disable ping
- Change ssh default port 21 to something else.
Got the ideas from networkchuck
Did this on the proxmox host as well as all VMs.
Any suggestions?
UDM’s regular built in threat filtering, good firewall rules, updated services, and not opening up unnecessarily to the internet. And be vigilant but don’t worry too much about it. That’s it.