We have three sets of computers: clients, a single proxy and multiple servers.
The clients (many) want to connect to the servers (many) using TCP on a specific and consistent port. Currently they do this directly. The connections always originate from the clients. And everything is happy and the world is good.
However, we would like to introduce a proxy / gateway / router to the equation. The goal is to bind a static IP address to the "proxy" so that the servers see all traffic as originating from a static IP address.
The clients make requests to multiple servers using multiple protocols (for example, they also make http requests). We only want to "proxy" a single protocol. All other protocols should be allowed to route as usual.
I think that this problem could be re-framed for any protocol. As it happens, the protocol (port) is LDAP. But I think this is pretty irrelevant (unless there's a nice, convenient little piece of LDAP-proxy software out there).
I don't believe it matters, but our environment is AWS. We are not running a VPC. Why it might matter is that the machines only have a single network interface.
We have tried several approaches, but haven't managed to get this to work. I would welcome your input - even if it is to tell us that what we want to do is impossible!