Fixed issue with moby block IP forwarding and hence our container rou…

…ting.

Relevant issues:
* moby/moby#28257
* boot2docker/boot2docker#1364

cli/dinghy/dnsdock.rb

@@ -36,6 +36,7 @@ def up
     unless resolver_configured?
       configure_resolver!
     end
+    fix_moby_iptables!
     route_add!
   end
 
@@ -87,6 +88,12 @@ def route_add!
     flush_dns_cache!
   end
 
+  # Moby has changed how they accept IP forwarding.
+  # @see https://github.com/boot2docker/boot2docker/issues/1364
+  def fix_moby_iptables!
+    machine.ssh("sudo /usr/local/sbin/iptables -P FORWARD ACCEPT")
+  end
+
   def route_remove!
     System.capture_output do
       system!("removing route", "sudo", "route", "-n", "delete", DOCKER_SUBNET)