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VMware ACE Administrator’s Manual
Understanding NAT
Network address translation — or NAT — provides a simple way for virtual machines
to use most client applications over almost any type of network connection available
to the host. The only requirement is that the network connection must support
TCP/IP.
NAT is useful when you have a limited supply of IP addresses or are connected to the
network through a non-Ethernet network adapter. NAT works by translating addresses
of virtual machines in a private VMnet network to that of the host machine. When a
virtual machine sends a request to access a network resource, it appears to the
network resource as if the request came from the host machine.
NAT uses the host’s own network resources to connect to the external network. Thus,
any TCP/IP network resource to which the host has access should be available
through the NAT connection.
The chief advantage of NAT is that it provides a transparent, easily configured way for
virtual machines to gain access to network resources.
Using NAT
The NAT device is connected to the VMnet8 virtual switch. Virtual machines
connected to the NAT network also use the VMnet8 virtual switch.
The NAT device waits for packets coming from virtual machines on the VMnet8 virtual
network. When a packet arrives, the NAT device translates the address of the virtual
machine to that of the host before forwarding the packet to the external network.
When data arrives from the external network for the virtual machine on the private
network, the NAT device receives the data, replaces the network address with that of
the virtual machine and forwards the data to the virtual machine on the virtual
network. This translation occurs automatically and requires minimal configuration on
the guest and the host.
The Host Computer and the NAT Network
The host computer has a host virtual adapter on the NAT network (identical to the
host virtual adapter on the host-only network). This adapter allows the host and the
virtual machines to communicate with each other for such purposes as file sharing.
The NAT device never forwards traffic from the host virtual adapter.
DHCP on the NAT Network
In order to make networking configuration easy, a DHCP server is automatically
installed when you install VMware ACE. Virtual machines running on the network with