  - better handling of "encryption" layers, let the user deside if tunnel/transport mode,
      or ah, or ipcomp (or only a few of them). something like --use esp-tun:ah:ipcomp.
      First use ipcomp to compress the data stream, then use ah on the package and then put
      the package into an esp tunnel.
  - better stand alone script (also with autodetection of local IPs) - could be quite hard!!
