IPSecとNAT
UDP Encapsulation of IPSec Packets
http://www.ietf.org/internet-drafts/draft-ietf-ipsec-udp-encaps-06.txt
Negotiation of NAT-Traversal in the IKE
http://www.ietf.org/internet-drafts/draft-ietf-ipsec-nat-t-ike-06.txt
UDP Encapsulation of IPSec Packets
http://www.ietf.org/internet-drafts/draft-ietf-ipsec-udp-encaps-06.txt
Negotiation of NAT-Traversal in the IKE
http://www.ietf.org/internet-drafts/draft-ietf-ipsec-nat-t-ike-06.txt