Virtualbox (http://www.virtualbox.org/) is a virtualzation platform. I use it to test out new Linux distributions as well as to run some limited tests of new software for customers. It can run on Linux or windows hosts and can run quite a few guest operating systems. Installation in Ubuntu is a snap. First enable the VirtualBox repo if you don't want to use the open source edition. Edit your /etc/apt/sources.list. I added this to mine for gutsy:
deb http://www.virtualbox.org/debian gutsy non-free
FireHOL allows you to configure your firewall using a "high-level" language that anyone can read. Meanwhile, it allows all the power and flexibility you have come to expect from iptables.
I just recently wrestled with my little smb setup here to tighten the grip on who might be accessing my share. My intention is to simply share my own smb share I have running in VmWare with my XP host. My XP host is logged into a domain server not to the local machine. The Linux I have installed in VmWare is FC5 running from USB drive and using the NAT networking setting. My company has blocked DHCP to only those machines authenticated with by the domain server. I originally used the KDE Control Center to setup my smb sharing homes.
I am doing some research for Dr. Tang, a professor in the MSU Computer Science Department. He wants to find an optimal set of channels for a wireless mesh network for some networking metric. Some common metrics are Quality of Service (QoS), throughput, and latency. Of course any algorithms he wants to try out require testing in the simulation environment we use, called OpNet. OpNet is an unweildly beast, and I spend most of my time wrestling with it. The hard part is that for his research, Tang wants each node to have multiple radios. The simulator really doesn't like that.