I currently have a situation where I have around 20 machines across 7 or so locations where each of those locations is firewalled. We need to be able to pull up a remote desktop on these machines (windows XP and 7 machines).
Currently we are using Logmein Hamachi for access to the machines but would really like to move away from this solution as we have trouble with it crashing and users shutting it down.
We are interested in both hosted and non-hosted solutions. We have a linux server here that could be used to host our own solution if one is available. It is preferable that the solution be relatively light weight (at least when we aren't actually remoting in).
Any help would be appreciated.
Update: The situation is one where we administer a few machines at each site but the IT department administers the rest as well as the network. Unfortunately they are unwilling to open any external ports or allow any server hardware at these sites.
Another update: A possible solution that I have considered is to run a VPN server on our server and setup the clients to use split tunneling. It seems this would work to grant us access but I'm not very familiar with VPNs so I'm not certain.