* write better documentation

* Adapt it to IPv6 - better yet, any protocol.
  * this would require to base routing on MAC addresses instead of IP
    addresses, as is done now. If this can be done, IPX is also
    supported.
  * let tinc assign a MAC address to the tap device, based on some
    whacky number

* add a digital signature to each packet, using HMAC

* enable encryption using other ciphers (IDEA)
  * the library is already included, but it cannot be used.

* allow multiple outgoing links, or a list of them, so that if a host
  is not available, that we can select another from the list.

* support for multiple protocols; PPTP, IPSec, NIAS, L2TP,...
