default.cfg Improved DOS protection

- use permissions module to have the equivalent of a white list, a list
  of IPs that are trusted. This module is used together with db_text and
  the list of IPs and IP ranges will be specified in the address dbtext
  file.
- drop requests that have no To domain or a To domain consisting of an
  IP.
- reply to Options from outside only if the RURI domain is not IP.
Added dbtext files.