I am trying to set up a PIX501 so that an outside W2K mobile user can IPSEC/L2TP into the "inside". I'm using PSK.
It works perfectly without a NAT box in between, but when I have to cross NAT (using NAT-T), phase 2 negotiation fails. I have enabled NAT-T in the PIX and it is always enabled in MS. I also don't think that this is a port blocking or compatible policy issue.
I've found the most likely reason. During phase 2 negotiation, the Microsoft client adds a payload "ID_FQDN" which the PIX rejects ("unknown src id_type 2"). MS client keeps retrying but PIX keeps rejecting.
MS client does not send this when NAT-T is not required. It only sends it when a NAT device is detected in the path (through the NAT-D exchange).
This seems like a simple incompatibility between MS's interpretation of NAT-T RFCs and Cisco's.
1) Is this the problem?
2) How do I work around it?
TIA
Keith
