The MOBIKE IKEv2 extension (RFC 4555) allows an initiator to change its network attachement point (e.g. roam to an other interface/address).
strongSwan implements MOBIKE by watching interfaces, addresses and routes. If the
configuration changes, route lookups are done to find a better path than the
current one and, if necessary, the path is changed using a MOBIKE update
strongSwan is running the MOBIKE protocol per default. MOBIKE can be disabled on
a per-connection basis, though, by adding the parameter
mobike = no to the
corresponding connection definition in
swanctl.conf. Please be aware that with MOBIKE
enabled, strongSwan will switch to UDP port 4500 starting with the IKE_AUTH request,
which includes a
MOBIKE_SUPPORTED notification, even if no NAT has been detected.
Thus make sure to open the NAT-traversal port UDP/4500 on any firewalls en route.