Specifications

Table Of Contents
VMware, Inc. 191
Chapter 7 Networking
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!hostonly!network).!This!adapter!allows!the!host!and!the!virtual!
machines!to!communicate!with!each!other!for!such!purposes!as!file!sharing.!The!NAT!
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!Server.!Virtual!machines!running!on!the!network!
with!the!NAT!device!can!dynamically!obtain!their!IP!addresses!by!sending!out!DHCP!
requests.!The!DHCP!server!on!the!NAT!network,!which!is!also!used!in
!hostonly!
networking!configurations,!dynamically!allocates!IP!addresses!in!the!range!of!
<net>.128!through!<net>.254,!where!<net>!is!the!network!number!assigned!to!your!NAT!
network.!VMware!Server!always!uses!a!Class!C!address!for!NAT!networks.!IP!
addresses!<net>.3!through!<net>.127!can!be!used!for!static!IP!addresses.!IP!
address!
<net>.1!is!reserved!for!the!host!adapter;!<net>.2!is!reserved!for!the!NAT!device.
In!addition!to!the!IP!address,!the!DHCP!server!on!the!NAT!network!also!sends!out!
additional!configuration!information!that!enables!the!virtual!machine!to!operate!
automatically.!This!information!includes!the!default!gateway!and!the!DNS!
server.!In!
the!DHCP!response,!the!NAT!device!instructs!the!virtual!machine!to!use!the!IP!address!
<net>.2!as!the!default!gateway!and!DNS!server.!This!causes!all!IP!packets!destined!for!
the!external!network!and!DNS!requests!to!be!forwarded!to!the!NAT!device.
DNS on the NAT Network
The!NAT!device!acts!as!a!DNS!server!for!the!virtual!machines!on!the!NAT!network.!
Actually,!the!NAT!device!is!a!DNS!proxy!and!merely!forwards!DNS!requests!from!the!