+register_format('mac-addr', \&pve_verify_mac_addr);
+sub pve_verify_mac_addr {
+ my ($mac_addr, $noerr) = @_;
+
+ # don't allow I/G bit to be set, most of the time it breaks things, see:
+ # https://pve.proxmox.com/pipermail/pve-devel/2019-March/035998.html
+ if ($mac_addr !~ m/^[a-f0-9][02468ace](?::[a-f0-9]{2}){5}$/i) {
+ return undef if $noerr;
+ die "value does not look like a valid unicast MAC address\n";
+ }
+ return $mac_addr;
+
+}
+register_standard_option('mac-addr', {
+ type => 'string',
+ description => 'Unicast MAC address.',
+ verbose_description => 'A common MAC address with the I/G (Individual/Group) bit not set.',
+ format_description => "XX:XX:XX:XX:XX:XX",
+ optional => 1,
+ format => 'mac-addr',
+});
+