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?
Internet > Firewall, IP Whitelist, IPS/IDS yada yada> DMZ / VLAN > > Proxmox /w FW:$true (rule only for game ports) > GameServer > Deny all traffic from GameServer to go anywhere but internet
Proxmox server has firewall, all the hosts on proxmox have firewall enabled (in proxmox). Only allow my main device to access. No VLAN crosstalk permitted.
I don't bother with anything else internally, if they're inside they deserve to SSH with my default root / password credentials