As you might know, the latest Varnish Enterprise release (6.0.6r2) adds support for in-process, or native, TLS. What does this mean, though, and why add this feature, why now?
HAProxy’s proxy protocol has been supported as part of Varnish 4.1 for a few months now. The proxy protocol's main purpose is to transport client connection information from the originating source requesting the connection. It adds a small header about the origin connection.