my $file = '/pfad/zur/datei.txt';

my @inactive_ports;

{
    local $/ = "\n\n";
    open my $fh, '<', $file or die $!;
    while ( my $port_data = <$fh> ) {
        if ( $port_data =~ /Status\s*:\s*Inaktiv/ ) {
            my ($port) = $port_data =~ /Port\s*:\s*(\d+)/;
            push @inactive_ports, $port;
        }
    }
    close $fh;
}

print "Inactive Ports: @inactive_ports\n";