The portreserve program aims to help services with well-known ports
that lie in the bindresvport() range.  It prevents portmap (or other
programs using bindresvport()) from occupying a real service's port by
occupying it itself, until the real service tells it to release the
port (generally in its init script).

Example usage:

o The CUPS package could contain a file /etc/portreserve/cups,
  containing the string 'ipp'.
o At boot, the portreserve daemon starts, and binds to the ipp port.
o When portmap starts, it cannot bind to the ipp port since it is in
o When CUPS starts, it runs 'portrelease cups' to make the daemon let
  go of the ipp port.
o CUPS should require the portreserve package.

Tim Waugh