@@ -44,6 +44,7 @@ func (srv *Server) Help() string {

 		{"ps", "Display a list of containers"},

 		{"pull", "Download a tarball and create a container from it"},

 		{"put", "Upload a tarball and create a container from it"},

+		{"port", "Lookup the public-facing port which is NAT-ed to PRIVATE_PORT"},

 		{"rm", "Remove containers"},

 		{"kill", "Kill a running container"},

 		{"wait", "Wait for the state of a container to change"},

@@ -311,6 +312,30 @@ func (srv *Server) CmdInspect(stdin io.ReadCloser, stdout io.Writer, args ...str

 	return nil

 }

+func (srv *Server) CmdPort(stdin io.ReadCloser, stdout io.Writer, args ...string) error {

+	cmd := rcli.Subcmd(stdout, "port", "[OPTIONS] CONTAINER PRIVATE_PORT", "Lookup the public-facing port which is NAT-ed to PRIVATE_PORT")

+	if err := cmd.Parse(args); err != nil {

+		cmd.Usage()

+		return nil

+	}

+	if cmd.NArg() != 2 {

+		cmd.Usage()

+		return nil

+	}

+	name := cmd.Arg(0)

+	privatePort := cmd.Arg(1)

+	if container := srv.containers.Get(name); container == nil {

+		return errors.New("No such container: " + name)

+	} else {

+		if frontend, exists := container.NetworkSettings.PortMapping[privatePort]; !exists {

+			return fmt.Errorf("No private port '%s' allocated on %s", privatePort, name)

+		} else {

+			fmt.Fprintln(stdout, frontend)

+		}

+	}

+	return nil

+}

+

 // 'docker rmi NAME' removes all images with the name NAME

 func (srv *Server) CmdRmi(stdin io.ReadCloser, stdout io.Writer, args ...string) error {

 	cmd := rcli.Subcmd(stdout, "rmimage", "[OPTIONS] IMAGE", "Remove an image")