The routes direct traffic matching the remote traffic selector to the
TUN device.
If the remote traffic selector includes the IKE peer a very specific route
is installed to allow IKE traffic.
This has the same meaning as omitting left/rightsubnet, i.e. replace it
by the IKE address. Supporting %dynamic allows configurations with multiple
dynamic selectors in a left/rightsubnet, each with potentially different
proto/port selectors.
When a connection has a single pool that queries recursively the DHCP backend,
we shouldn't return any attributes directly from DHCP when queried for that
pool.
This new flag gives the kernel-interface a hint how it should priorize the
use of newly installed SAs during rekeying.
Consider the following rekey procedure in IKEv2:
Initiator --- Responder
I1 -------CREATE-------> R1
I2 <------CREATE--------
-------DELETE-------> R2
I3 <------DELETE--------
SAs are always handled as pairs, the following happens at the SA level:
* Initiator starts the exchange at I1
* Responder installs new SA pair at R1
* Initiator installs new SA pair at I2
* Responder removes old SA pair at R2
* Initiator removes old SA pair at I3
This makes sure SAs get installed/removed overlapping during rekeying. However,
to avoid any packet loss, it is crucial that the new outbound SA gets
activated at the correct position:
* as exchange initiator, in I2
* as exchange responder, in R2
This should guarantee that we don't use the new outbound SA before the peer
could install its corresponding inbound SA.
The new parameter allows the kernel backend to install the new SA with
appropriate priorities, i.e. it should:
* as exchange inititator, have the new outbound SA installed with higher
priority than the old SA
* as exchange responder, have the new outbound SA installed with lower
priority than the old SA
While we could split up the SA installation at the responder, this approach
has another advantage: it allows the kernel backend to switch SAs based on
other criteria, for example when receiving traffic on the new inbound SA.
With the new implementation the plugins don't have to be listed in any
special order, dependencies are properly resolved. The order only
matters if two plugins provide the same feature.
Tobias Brunner