I have a requirement to secure all communications between our Linux instances on Amazon EC2 - we need to treat the EC2 network as compromised and therefore want to protect the data that's being transferred within the EC2 subnet(s). The instances to secure will all be on the same subnet. I'm a Windows bod with limited Linux abilities, so am familiar with IPSec terminology and can find my way around Linux, but haven't got a clue when it comes to setting up Linux IPSec environments.
Can anyone throw me some information for setting up IPSec between all (Linux) hosts on a subnet please? I can only find information that pertains to site-to-site connections, or host-to-host connections and nothing that covers all Lan communication. We're currently using OpenSwan for site-to-site VPNs if that helps.
Updated with more information
This is an example config (very basic to connect between two hosts using a pre-shared key):
conn test type=tunnel auto=start authby=secret left=10.0.2.4 right=10.0.2.5 pfs=yes
If I now want to secure all traffic between 4 hosts for instance (or 8,10,100 etc), is there a way to make the left and right parameters more generic, so they mean 'encrypt traffic between all hosts' rather than having to explicitly specify a left and right host.
My goal would be to achieve a generic configuration that has no hardcoded host IP's (subnets would be OK), so that we could include the configuration in our EC2 image.