# Warning: untested...

sub expand_ports {
    my $port = shift;
    my %ports;
    foreach my $range (split /\s*,\s*/, $port) {
        if ($range =~ /^\d+$/) {
            $ports{$range}++;
        } elsif ($range =~ /^\s*(\d+)\s*-\s*(\d+)\s*$/) {
            @ports{$1..$2} = ($1..$2);
        } else {
            die "Bad port spec";
        }
    }
    return sort keys %ports;
}