A Luxembourgish court decided that Lufthansa has to reimburse passengers who are affected by a strike. According to the judge, the airline can't claim extraordinary circumstances. It is the second ruling of this kind in a short time.
If you were at the check-in counter on time, having valid travel documents with you and were still denied boarding you are entitled to several rights and services.
In case your booked flight was cancelled, you are entitled to several rights and services.