[Mobike] issue 3: nat traversal

[James Kempf]

Francis,

> => simple: I propose a configuration "NAT forbidden" bit:
>  - if it is on NAT prevention is used and on the detection of a NAT
>    IKE/MOBIKE is aborted with an error status.
>  - if it is off NAT detection is used and on the detection of a NAT
>    the NAT traversal feature of IKE is activated. If a NAT is suspected
>    during an active IKE/MOBIKE session (cf previous discussion) then the
>    session is aborted and IKE is restarted with NAT detection... Note it
is
>    possible to enforce the detection of a NAT at the price of a bidding
>    down attack issue, and the IPsec WG decided to not support NAT
traversal
>    detection/activation in the middle of IKE sessions.
>

This sounds pretty reasonable to me. I think it should handle the case of
movement from outside a NAT to inside. Though it would require IPsec to be
rerun, I think this is a feature, since, as you mention, it avoids bidding
down.

What about moving from inside to outside?

            jak