I am using a rackspace cloud environment to host a server farm. The problem i've run into is that Rackspace shares all internal network traffic on a single subnet (or rather, all the servers in what they call a 'huddle'). This is not ideal, as I need to pass some sensitive information between servers and do not want to take the risk of being sniffed. We could use ssl, but that would require a great deal of re-architecting the application.
Rackspace suggested creatinga VPN between servers. This seems like the easiest solution at this point, however, i'm looking for a vpn solution that is stable and works well in a backend server environment with lots of traffic.
The servers are a mix of Windows and Linux servers. Keep in mind that the vpn has to work without an interactive user logged in. As such, it has to be something that is service friendly. So, client-side vpn's like Hamachi aren't really viable, nor do I want a solution that requires an outside server.
I'd like to avoid any options that require a great deal of configuration to make work. This leaves out IPSec and OpenVPN (both of which give you very powerful low-level control, but require a lot of configuration)
I thought it was relatively obvious from my requirements, but I cannot have a point-to-point solution, it needs to be a private subnet not clients connecting to a single server. And I definitely don't want to create configurations to connect to the entire set of permutations of servers.