Preparing Proxmox for TrueNAS

Introduction
This page walks through setting up networking in preparation for TrueNAS.
Prerequisites
Your setup before is expected to be:
The machine is physically connected to some form of upstream internet;
The only network bridge that currently exists is the default 
vmbr0.
Steps
Creating the inter-VM network bridge
To allow virtual machines to communicate safely, we will be creating a new bridge 
vmbr1. VMs that require direct communication with each other with no additional routing in between them will use this bridge to talk to each other.
Select your Proxmox node.
Go to System > Network
Click Create > Linux Bridge:
A popup should appear. Fill it out like so:
The IPv4 we set here is the address at which the Proxmox node itself will be reachable on this bridge. If left empty, it will not be reachable by VMs.
Click Create.
Apply the changes:
The inter-VM network bridge is now created, and Proxmox itself is reachable on the bridge via the address 
192.168.255.10.
You are now ready to install TrueNAS.