diff --git a/mxnetctl/mxnetctl b/mxnetctl/mxnetctl
new file mode 100755
index 0000000..c571746
--- /dev/null
+++ b/mxnetctl/mxnetctl
@@ -0,0 +1,254 @@
+#! /usr/bin/perl
+use strict;
+use warnings;
+
+use Getopt::Long;
+
+# options
+
+our ($opt_quiet,$opt_noop,$opt_ignore_hw);
+use constant OPTIONS => (
+	'quiet'     => \$opt_quiet,
+	'noop'      => \$opt_noop,
+);
+
+sub USAGE {
+	return <<"__EOF__";
+usage: $0
+  start   [options]
+  stop    [options] # (ignored)
+  upgrade           # switch from eth to net
+
+options:
+  --quiet      : do not log actions
+  --noop       : dry run
+
+__EOF__
+}
+ 
+sub scandir {
+	my ($dirname)=@_;
+	opendir my $dir,$dirname or die "$dirname: $!\n";
+	return sort grep !/^\./,readdir $dir;
+}
+
+sub slurpfile {
+	my ($path)=@_;
+	open my $fh,'<',$path or die "$path: $!\n";
+	return join ('',<$fh>);
+}
+
+sub slurpfile_chomp {
+        my $data=slurpfile($_[0]);
+        chomp($data);
+        return $data;
+}
+
+sub network_devices {		# -> ( 'bond0','dummy0','eth0','eth1','eth2','eth2.43','eth3','eth4','eth5','lo','sit0' )
+	return grep -d "/sys/class/net/$_",scandir('/sys/class/net');
+}
+
+sub network_hardware_devices {	# -> ( eth0','eth1','eth2','eth3','eth4','eth5' )
+	return grep -e "/sys/class/net/$_/device",network_devices();
+}
+
+
+sub get_hw_address {		# 'eth1' -> '00:1b:21:79:76:67'
+	my ($dev)=@_;
+	my $path="/sys/class/net/$dev/address";
+	return slurpfile_chomp($path);
+}
+
+
+our %HW_TO_DEV;		# ( '00:1b:21:79:76:67' => 'net02' , ... )
+our %DEV_TO_HW;		# ('net02'=>'00:1b:21:79:76:67', ... )
+our $CHANGES;
+
+
+sub register_stable {
+	my ($hw,$dev)=@_;
+
+	# force one-to-one mapping, even if file is erroneus
+	
+	exists $DEV_TO_HW{$dev} and delete $HW_TO_DEV{$DEV_TO_HW{$dev}};
+	exists $HW_TO_DEV{$dev} and delete $DEV_TO_HW{$HW_TO_DEV{$hw}};
+	
+
+	$HW_TO_DEV{$hw}=$dev;
+	$DEV_TO_HW{$dev}=$hw;
+	$CHANGES++;
+}
+
+
+sub read_mxnet {
+	%HW_TO_DEV=();
+	%DEV_TO_HW=();
+	-r '/etc/local/mxnet' or return;
+	open my $file,'<','/etc/local/mxnet' or die "/etc/local/mxnet: $!\n";
+	while (<$file>) {
+		s/#.*//;
+		/\S/ or next;
+		my ($hw,$dev)=split;
+		register_stable($hw,$dev);
+	}
+	$CHANGES=0;
+}
+
+sub write_mxnet {
+	my $mxnet;
+	unless ($opt_noop) {
+		open my $mxnet,'>',"/etc/local/mxnet" or die "/etc/local/mxnet: $!\n";
+		print $mxnet "# generated ".scalar(localtime)." by $0\n\n";
+		for my $dev (sort keys %DEV_TO_HW) {
+			print $mxnet $DEV_TO_HW{$dev},' ',$dev."\n";
+		}
+		print $mxnet "\n";
+
+#		open my $out,'>',"/etc/local/mxnet-udev.rules" or die "/etc/local/mxnet-udev.rules: $!\n";
+#		print $out "# generated ".scalar(localtime)." by $0\n\n";
+#		for my $dev (sort keys %DEV_TO_HW) {
+#			print $out qq'SUBSYSTEM=="net", ACTION=="add", ATTR{address}=="$DEV_TO_HW{$dev}", NAME="$dev"\n';
+#		}
+	}
+}
+
+sub get_unused_name {
+	my $next_name=0;
+	while(1) {
+		my $name=sprintf 'net%02d',$next_name++;
+		exists $DEV_TO_HW{$name} or return $name;
+	}
+}
+
+
+sub rename_if {
+	my ($src,$dst)=@_;
+	warn "rename $src to $dst\n" unless $opt_quiet;
+	unless ($opt_noop) {
+		if (defined $src =~ /^eth/) {
+			system 'ip','link','set',$src,'name',$dst,'alias',$src;  # continue on error
+			$? and warn "failed to rename $src to $dst\n";
+		} else {
+			system 'ip','link','set',$src,'name',$dst;  # continue on error
+			$? and warn "failed to rename $src to $dst\n";
+		}
+	}
+}
+
+
+sub preferred_device_name {
+	my ($dev,$hw)=@_;
+
+	exists $HW_TO_DEV{$hw} and return $HW_TO_DEV{$hw};	# configured
+	$dev =~ /(\d+)/;
+
+	my $new_dev=sprintf 'net%02d',$1;		# stable number if free
+	unless (exists $DEV_TO_HW{$new_dev}) {
+		register_stable($hw,$new_dev);
+		return $new_dev;
+	}
+
+	$new_dev=get_unused_name();			# any free new number
+	register_stable($hw,$new_dev);
+	return $new_dev;
+}
+
+
+
+our $TMP_NUM=0;
+sub out_of_the_way {
+	my ($dev)=@_;		# only 'netXX' or 'ethX' - never 'tmpXX'
+	
+	-e "/sys/class/net/$dev/device" or return;
+	
+	my $i = $dev=~/(\d+)/;
+	rename_if($dev,sprintf('tmpnet%02d',$TMP_NUM++));
+}
+
+sub start {
+	read_mxnet();
+	
+	# 1: rename configured ethX and netXX devices to configured netXX - move away conflicting devices
+
+	for my $dev (grep /^(eth|net)(\d+)/,network_hardware_devices()) {
+		my $hw=get_hw_address($dev);
+		my $new_dev=preferred_device_name($dev,$hw);
+		if ($dev ne $new_dev) {
+			out_of_the_way($new_dev);
+			rename_if($dev,$new_dev);
+		}
+	}
+
+	# 2 : rename moved away devices to netXX
+
+	for my $dev (grep /^(tmpnet)(\d+)/,network_hardware_devices()) {
+		my $hw=get_hw_address($dev);
+		my $new_dev=preferred_device_name($dev,$hw);
+		rename_if($dev,$new_dev);
+	}
+
+	#if ($CHANGES || ! -e "/etc/local/mxnet-udev.rules") {
+	if ($CHANGES) {
+		write_mxnet();
+	}
+}
+
+
+
+sub upgrade {
+	umask 022;
+
+	-d '/etc/local' or mkdir '/etc/local' or die "/etc/local: $!\n";
+
+	read_mxnet();
+	for my $dev (grep /^(eth|net)(\d+)/,network_hardware_devices()) {
+		my $hw=get_hw_address($dev);
+		my $new_dev=preferred_device_name($dev,$hw);
+	}
+	write_mxnet();
+
+	unlink "/etc/udev/rules.d/70-persistent-net.rules";
+
+	my $data=slurpfile('/etc/systemd/system/network.service');
+	unless ($data=~/mxnetctl/) {	
+		$data=~s#^ExecStart#ExecStart=/usr/sbin/mxnetctl start\nExecStart#m;
+		$data=~s/eth(\d+)/sprintf 'net%02d',$1/eg;
+		open my $out,'>','/etc/systemd/system/network.service' or die "/etc/systemd/system/network.service: $!\n";
+		print $out $data;
+		close $out;
+	}
+
+	warn "updated /etc/local/mxnet , /etc/systemd/system/network.service , /etc/udev/rules.d/70-persistent-net.rules - reboot to activate\n";
+}
+
+
+
+
+
+
+
+GetOptions(OPTIONS) or die USAGE;
+
+@ARGV>=1 or die USAGE;
+
+my ($cmd)=@ARGV;
+
+
+if ($cmd eq 'start') {
+	start();
+} elsif ($cmd eq 'stop') {
+	;
+} elsif ($cmd eq 'upgrade') {
+	upgrade();
+	;
+} else {
+	die USAGE;
+}
+
+
+
+
+
+
+
+