An IPsec tunnel connecting the subnets behind the gateways moon and
sun is set up. The authentication is based on Preshared Keys
(PSK). Unfortunately the secret keys of moon and sun do not
match, so that the responder cannot decrypt ISAKMP message MI3. The resulting
encrypted notification message cannot in turn be read by the initiator
moon. In order to avoid a notify-war, any further generation of
PAYLOAD_MALFORMED messages is suppressed.