It would be really great to have to forecast plugin included in libcharon-extra-plugins :)
The forecast plugin allows, when specified/permitted by the traffic selectors, to forward broadcast and multicast packets between clients and subnets. Multicast packets are widely used by "network discovery" protocols such as Zeronconf/Bonjour and SSDP. The forecast plugin permits to replay such packets in IPsec tunnels which allows services discovery (printers, DLNA, ...) across clients/subnets. Building the forecast plugin requires iptables development headers and the --enable-forecast flag to the ./configure options. Enabling the forecast plugin requires CAP_NET_RAW and the farp plugin (which is already available in the libcharon-extra-plugins package). The forecast plugin is described here: https://wiki.strongswan.org/projects/strongswan/wiki/Forecast
