I am looking for a way to have a postgresql database (running server version 9.1) replicated. I want the mirroring to be able to have one server (the slave) standing outside our firewall. I have been looking at slony and streaming replication - in both these cases, the slave server needs to talk back to the master, for security reasons, I would like that not to be the case. Ideally, I would like the master just to send the changes off to the slave without expecting any answers. are there any systems that act like this?
(Of course, I know that if the slave goes down, or for some other reason is not able to receive the data, the master will not know, but as we have other tools to keep an eye on server problems, this is acceptable)