A method of filtering a tunneled data packet comprising an outer header and an outer payload, the outer payload comprising an inner data packet comprising an inner header and an inner payload, where the value of at least one outer header field of the tunneled data packet is matched to a first rule, and...http://www.google.de/patents/US20030115328?utm_source=gb-gplus-sharePatent US20030115328 - Firewall for filtering tunneled data packets
