If you are just managing a few virtual machines for a client, then the client might try publishing the VMware Remote Console through Citrix in order to let the VAR gain remote access to a particular virtual machine. Or, the client could allow access to the Virtual Infrastructure Web Access page. More information can be found on this by searching for "remote console" in the VMware Infrastructure 3 online library.
There are a couple of remote access methods for Microsoft Virtual Server R2 as well. The client could either allow secure access to the Microsoft Virtual Server Administration site or they could allow the VAR to use the Virtual Machine Remote Control (VMRC) client (preferably through a secure connection like a Citrix published application). More information on the VMRC client can be found at Microsoft technet.
If the client is using a Xen-based solution like Xensource, then the client can provide remote access to the VAR through a xend (xen daemon) solution. Xend can be controlled through an http-based protocol. A list of third-party virtual machine management tools for Xen can be found on this VMBlog post.
For Virtuozzo virtual private servers (vps), the client can provide Remote Desktop Protocol (RDP) access to each Virtual Private Server. Either through a straight RDP connection or through publishing an RDP connection through something like Citrix. More information about this can be found from this article at the SWSoft Web site.
This was first published in February 2007