* 443 - HTTPS if you optionally [[Access_HDA_over_SSLAccess HDA over SSL]].
* 445 - Samba File Sharing (port for your network shares)
* 1194 - VPN
Here is the minimum iptables firewall rules required for your HDA to still function as an HDA. These rules do not include any extra services you have enabled such as SSH (port 22), VNC (port 5902), MiniDLNA (port 8200), etc. For extra apps and services you'll have to look up documentation on the App you're using.