HIPL includes also experimental partial support for ICE-based NAT traversal. The extensions do not use STUN.

The extensions allow two end-hosts located in different private address realms to communicate over HIP with each other. In other words, you place both client and server software behind NAT boxes and connect them using HIP. The benefit of using HIP for this approach in contrast to some other alternatives is that HIP-based approach does not require changes in the application software and works also with IPv4-based applications.

The use of the service requires a HIP-ESP Relay middlebox that relays HIP control and ESP data traffic. You can use one the InfraHIP servers or set up your own as instructed in Chapter 6, Using HIP Rendezvous and HIP Relay Server/Mechanisms. Both Initiator and Responder must be configured with "hipconf nat ice-udp". Then Initiator must run the base exchange throught the relay server.