Want to build a safe secure redundant load balanced corporate infrastructure all inside one box?
Here are some simple DIY plans.
What is required is a dual nic server, with a installed virtual machine manager capable of supporting a virtual networks along with bridged connections to the intranet and internet.
Here is the diagram of the layout of your secure network:
The thinking behind this is to protect your servers from attacks from the internet. By passing all traffic from the first physical nic into a firewall virtual machine and then onto the virtual network prevents many common attacks, yet provides effective access to all resources from the outside and inside your corporation. The addition of a load balancer virtual machine allows the addition of multple http or mail servers to cover the demands. By adding a second virtual network for the database and http server it prevents bottlenecks on the main virtual network and secures the database server from outside attacks.
Some other ideas include having a VPN virtual machine to allow direct access from the primary physical nic to the secondary nic, bypassing the firewall and virtual network.
Here are some great pre made virtual images to use for your secure virtual network:
Virtual machines are not protected by any firewall software on the host operating system. The reason for this is that the virtual machines are essentially connected to the network at layer 2 while most conventional firewalls operate at layer 3 or higher (http://en.wikipedia.org/wiki/OSI_model). As such virtual machines should always have appropriate fire walling software enabled. If your guest operating system does not have firewall software readily handy (or you do not want to install a software firewall in the guest operating system) using Shared Networking under Virtual PC (as opposed to connecting the virtual machine directly to the network) will gain you a modicum of network security as - like with most NAT routing solutions - external network entities will be unable to communicate directly with your virtual machine. source
