Bridged Adaptor vs NAT.

By | February 18, 2019

There are 2 main network choices when you installing virtual machine: Bridged adapter and NAT (Network address translation). The bridged adapter option connect new virtual device directly to the network adapter installed on the physical host device. The IP address assigned to the virtual machine belongs to the same subnet as the physical device IP address related to the same network adapter. Usually the selection is preferable because it simplifies networks communication between host and guest.
NAT option creates new private subnet which connected to the host subnet though the router. It is more complicated but may be reasonable to use because of saving IP address of host network or restrict access to private subnet from exterior. The images below explain connection particularities of these to selections:

Let us begin with Bridged Adapter.

Guest and host machines belong to the same subnet and both are connected to the same gateway.

Host machine network configuration looks like this:

Guest machine network configuration for bridged adapter option:|

Now select NAT option for virtual machine:

Guest machine belongs to different subnet and has own gateway connected to host subnet:

Host machine network configuration is the same as above, but guest’s configuration was changed:

If interface does not show IP address add it manually, using ip command:

ip a addr dev eth0

Then specify routing:

ip route add default via src metric 100

Now to get access to guest’ network port forwarding is required. Every server port on guest machine should be configured for forwarding, for example ssh port 22:

Now if you want to ssh guest machine from host subnet putty session setup will look like this (based on selected ssh port forwarding, picture above):

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