Opportunistic mode has two benefits. First, you don't have to know the HIT of the peer. This is makes HIP more suitable to "ad-hoc" environments where preconfiguration of HITs is difficult. Second, the opp. mode implementation allows the use of IPv4 addresses at the application. This way, even IPv4-only legacy applications can benefit from the security and mobility features of HIP.
Opportunistic mode is not compiled by default. In order to use Opportunistic mode enabled HIP, the following steps are needed:
Move to top level of HIPL
e.g. cd hipl
Run autogen.sh
./autogen.sh
Run make
make
Run hip daemon on both "crash" and "oops"
hipd/hipd
. Using hipconf tool to set HIP Opportunistic mode on both hosts manually. "tools/hipconf set opp on|off" command is used to enable/disable opportunistic mode. By default it is on.
Now the opportunistic mode is enabled. To test Opportunistic mode, you need to remove crash's HITs and name from /etc/hip/hosts, and then following the steps in Chapter 6, Testing a HIP connection between two locally connected hosts.