Shorewall and Proxmox VE Cluster Configuration
This is a follow up article describing how to use Proxmox VE and Shorewall together. This article focus on using Shorewall within your Proxmox cluster. If you have not read the first article I recommend that you do so, it will aid your understanding with what is going in this one.
Network Layout and Shorewall Configuration
We are going to be using a bridging configuration. This is what Proxmox VE uses with by default. Bridging allows for easy migration of hosts without having to re-configure the firewall each time a machine is migrated.
Proxmox VE does not come with a firewall by default there are several solutions to this problem but the most flexible and robust is integrating the Shorewall firewall. This document assumes a basic knowledge of the Shorewall program and will not cover all of Shorewall capabilities but will give you a good working model to get you started. For more advanced topics check out the Shorewall documentation.
Shorewall will have 3 zones: 1) the fw zone which is the Proxmox host, 2) the net zone which is the Internet and 3) the dmz zone which is where the virtual machines will reside. The hardware just has one network interface card; vmbr0 is a just a bridge interface.