Techniques for automatic firewall configuration in a virtual network environment are described. In one example embodiment, firewall rules are configured using virtual machine (VM) inventory objects. The firewall rules are then transformed by replacing the VM inventory objects in the configured firewall rules with associated Internet protocol (IP) addresses using an IP address management table (IPAM) table and a network address translation (NAT) table. The transformed firewall rules are then sent to a firewall engine for filtering communication from and to VMs running on a first machine on one or more computing networks and communication from and to VMs running on a second machine on one or more computing networks at a firewall according to the transformed firewall rules.