I have a vendor who uses an ASA at his end to build VPN tunnel to us. He gets the following error when he attempts to send traffic to us through the VPN tunnel. One thing to point out is that I am able to see his syn packet come to the destination host located behind my side of the tunnel as well seeing as the syn, ack packet but never seeing the return ack packet. The appliance at the other end of the tunnel generated this error in their ASDM:
Routing failed to locate next hop for TCP from outside:our host:our port to inside: their host: their port.
My thinking is that the TCP SYN,ACK is not getting to their host explaining why the last ACK of the TCP 3way handshake is never seen at my side.
Any comments would be appreciated