how to sync moodle and joomla groups

hi.
we have a component that enroll joomla usergroup to specefic course...
is there any way for this:
i want when i add user to some joomla group , then that user assign to group in moodle. is it possible? i want use this method to restrict some users to one activity in the course. for example when i add user to some joomla groups,then he can't attempt in quiz.(also i know that i need set restrict setting in the activity)

It's possible to achieve this but you may need extra Joomla/Moodle plugins.

1. You can set an action that when a user is in a joomla group, it adds a value to a custom Joomla profile field (we do this using Community Builder).
2. This is then mapped to a Moodle profile field (using Joomdle)
3. Finally Moodle assigns a group to users with this value in their profile field (using " Auto-group " plugin)

i use Community Builder too, and i can create map between moodle and CB
1-are you using Auto Action plugin for step1?
2-in now i have 500 user that i want close on activity in course for them.now i need sync these users to moodle or when they login sync automatically or what is the solution?
3-in that moodle plugin setting page, i can see Group by setting, are you mean set that? can you say how you config that moodle plugin?
4-with your suggestion , if i correct we don't need Auto group plugin, simply we can say in restrict activity setting , if userfield = foo then for example show or hide or other...