* The size of the database is limited in "database.h". You could
  rewrite this part, using b-trees or hash tables.

* The length of host descriptions is also limited in 'database.h'. I've
  set it to 255 chars per default.

* The return value of "external.pl" is not checked for LFs, CRs etc..

* IPv6 support is evil, it was mostly done to clean up the ipv4 range
  and to support a common structure. Will be fixed on one of the next
  releases.

* Need to add something like a timestamp to prevent dataloss on (system)
  crash.