I can not find any way to connect to a Docker daemon which requires authentication. The daemon must be listening on a TCP port and allow any client which can connect to that port full control of Docker on that system.

This is bad enough when the socket is only accessible within the host running the daemon since it gives any user on that host complete control of Docker, bypassing the default group-based security. The situation is completely unacceptable when accessing a Docker daemon on a different host from the Jenkins host.