Unable to launch the real device(iPhone & iPad) session in Mac machine

I have been trying to setup the environment in Mac to execute the automation scripts in real device using Appium 1.6.4 version.

Our project is build with Selenium-java.try to executing the scripts using selenium grid.

I have done the environment setup in the Mac machine by following the steps in this link : http://ift.tt/2qJRCuI

ios_webkit_debug_proxy -c <Connected device UDID>:27753 –d in terminal 

When I'm trying to execute the above command in terminal I'm getting the following error :

Could not connect to lockdownd. Exiting.: Permission denied
ss.remove_server_fd(4)
Unable to attach 5d59aeb93f96b07f94a4ac7c1e860c891d9493d9 inspector

Can anyone please help on this? or Is there any better way to done the iOS real device setup in mach machine?