while (<>)
{
        /^hostname/ and do {
                $host_section = 1;
                ++$tot;         # number of hostnames
        };
        if ($host_section) {
                print $_;
                ++$tot2;        # lines in host sections
                # do some processing...
        }
        /^end-of-hostname-pattern/ and do {
                $host_section = 0;
        };
}