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Sunday, January 8, 2012

TCP Source port change for the outgoing traffic from VM

When it comes to virtual  machines  (VM) management one of the big challenges to work with is the virtual network. When using VMware Workstation ( or Oracle VM VirtualBox) we can defined per VM how the added virtual network adapter should work.

There are multiple setting to choice for a single virtual network interface within VM:
 - Bridged
 - NAT
 - Host-only private network

Server received TCP network traffic has changed source port when comparing it to the original traffic that the VM sent out.

Applications that are port sensitive show wrong results (example: udptx )

By default a network adapter added to a VM uses NAT feature. It means that the outgoing traffic from the VM may be changed before it is going to be sent the next hope router in our real network. To overcome this behaviour we ave to change the network operational setting from NAT to Bridged.

If you lost the network connectivity after this change in your VM you have to additionally check and potentially change the default setting to what physical network device our default VMware bridge (VMnet0) is connected.

 - VMware workstation GUI -> Edit ->Virtual Network Editor : Vmnet0
 - Select the correct virtual network device (default is VMnet0)  from the list
 - Select a appropriate device from the device list under "Bridged to"

Workstation and Player Online Library

Workstation 8 doesn't work properly with bridge networking

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