I've been having persistent problems getting IPsec to work over IPv6 using ipsec-tools on Linux. IPsec works OK on IPv4. IPv6 works OK without IPsec. But with IPsec over IPv6, the "racoon" daemon from ipsec-tools failed to establish a security association (it tries a few times and gives up in a few minutes).
While researching this through Google (searching web and groups), I've found a few instances where people report problems similar to this. But in all such cases there is no resolution to the problem. Most of these are older, but some as recent as 2006. Searches with the ipsec and ipv6 keywords don't reveal any success reports (although such things would not usually get posted).
Does _anyone_ have IPsec working over IPv6? With ipsec-tools on Linux? If so, what is the magic incantation?