'Return a port for passive access, using C{self.passivePortRange}
attribute.'

def getDTPPort(self, factory):

    for portn in self.passivePortRange:
        try:
            dtpPort = self.listenFactory(portn, factory)
        except error.CannotListenError:
            continue
        else:
            return dtpPort
    raise error.CannotListenError('', portn, ('No    port    available    in    range    %s' % (self.passivePortRange,)))
