 | 1 | initial version |
Well, what does the ICMP message tell you? Destination unreachable/Protocol unreachable.
So, the capture server's network interface is receiving GRE packets, with which it doesn't know what to do. How is it to respond? Since the IPv4 protocol is attached to that interface, an ICMP message Destination unreachable/Protocol unreachable is send back.
How to prevent this? Remove the protocols from the capture interface.
