Coillte, Ireland's leading forestry company has a very good website to do with getting outdoors. They give information on alot of the forest trails and recreation sites that they own. There is a some very good information on Wild Camping and Leave No Trace Camping. As I understand it you can get a permit to camp but if you are willing to be responsible and leave no trace nobody is going to harass you looking for a permit. I hope this information is useful to some.
http://www.coillteoutdoors.ie/index.php?id=25&no_cache=1
http://www.coillteoutdoors.ie/index.php?id=25&no_cache=1