docker & Firewall ports

hi All, need small help, i have docker EE install on ubuntu 16.04 box, before Docker EE was installed check_mk agant for monitoring was working ok, post docker EE installation it stopped , i checked the port is blocked now, which is 6556 , as i know firewall is managed by Docker , how can i address this so that it works post reboot etc. KB did not helped - Thanks