+sub disable_ipv6 {
+ my ($iface) = @_;
+ return if !-d '/proc/sys/net/ipv6'; # ipv6 might be completely disabled
+ my $file = "/proc/sys/net/ipv6/conf/$iface/disable_ipv6";
+ open(my $fh, '>', $file) or die "failed to open $file for writing: $!\n";
+ print {$fh} "1\n" or die "failed to disable link-local ipv6 for $iface\n";
+ close($fh);
+}
+