Strongswan

Somehow working:

forecast {

   # Multicast groups to join locally, allowing forwarding of them.
   groups = 224.0.0.1,224.0.0.22,224.0.0.251,224.0.0.252,239.255.255.250

   # Local interface to listen for broadcasts to forward.
   interface = BRIDGE_LAN

   # Whether to load the plugin. Can also be an integer to increase the
   # priority of this plugin.
   load = yes

   # CHILD_SA configurations names to perform multi/broadcast reinjection.
   # reinject = mobile,linux

}

connections {

  linux {
     local_addrs  = 192.168.3.253
     remote_addrs = darkrealm.dyndns.org
     keyingtries = 0
     
     local {
        auth = pubkey
        certs = neorealm.crt
     }
     remote {
        auth = pubkey

certs = darkrealm.crt

     }
     children {
        linux {
           local_ts  = 192.168.2.0/24,192.168.3.0/24,224.0.0.0/4,fd00:ffff:bbbb::/64,ff00::/8 
           remote_ts = 192.168.0.0/24,192.168.1.0/24,224.0.0.0/4,fd00:ffff:aaaa::/64,ff00::/8 
           mark_in  = %unique
           mark_out = %unique

ipcomp = yes start_action = trap close_action = trap dpd_action = trap

}

     		}
     }

}