Hyper-V and OpenVPN

[sc:windows-category ]Having converted all my VMWare VM’s to Hyper-V was a relatively smooth process and they have been working quite well over the last several months, however I have found a slight quirk and that I haven’t been able to track down yet.

When I’m off site, I use OpenVPN to connect in to my network and then often use a virtual PC running on Hyper-V to work with.  This runs fine and under VMWare I could use the remote control application to place an Icon directly on my desktop to get to the Virtual system.  I have setup a similar Icon with Hyper-V and have used it from within the network without issue.

However, I recently tried to connect to the system from a remote location after having connected to OpenVPN and found that after a few seconds, the connection failed with an RPC error.

Curious, I retried the connection from inside the network, using OpenVPN and everything worked fine.

The Hyper-V manager exhibited the same behaviour.  Just using the standard RDP connection worked fine.

There must be something failing from the OpenVPN side, but I have yet to track down what it is.

The search continues…

Greg

Greg is the head cat at JumbleCat, with over 20 years of experience in the computer field, he has done everything from programming to hardware solutions. You can contact Greg via the contact form on the main menu above.

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Greg

Greg is the head cat at JumbleCat, with over 20 years of experience in the computer field, he has done everything from programming to hardware solutions. You can contact Greg via the contact form on the main menu above.

2 thoughts to “Hyper-V and OpenVPN”

  1. Hi,
    I just ported an “Remote Access Server” which uses OpenVPN for remote access from VMWare Server 1.x to Hyper-V (Windows 2008 R2, the OS in the VM is Windows XP).
    It runs in general but I have many, real many connection aborts.
    I tried several things (like diabling time synchronisation of the integration services and so on) but nothing helped until now.
    In the OpenVPN log I found the following messages when the connection breaks down:

    MULTI: multi_create_instance called
    Re-using SSL/TLS context

    TLS Error: TLS key negotiation failed to occur within 60 seconds (check your network connectivity)
    TLS Error: TLS handshake failed

    After reading all the FAQs and hints concerning this fault messages (firewall, router, …) I just changed the normal network card of the Hyper-V and now using the legacy network adapter.
    Until now the behavior is total different and this seems to be the solution for that problem!
    I do not know what the difference between these two types of adapters is but the normal adapter of the integration services seems to generate the described problems…

    I hope, this helps

    1. The difference is how Hyper-V emulates the network card. The legacy network adapter emulates 100% of the hardware of a standard network card and will work with any OS. The default network adapter in Hyper-V on the other hand is just a thin shim between Hyper-V and the built in driver in host Windows install. To use the shim you have to have an OS that supports it (like Windows) and a driver for it, OpenVPN doesn’t ship with a driver so it doesn’t work.

      The default is the shim because it takes up a lot less resources than the legacy adapter and most people are running Windows VM’s under Hyper-V which fully supports it.

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