Find MAC address dups in Proxmox environment, happen after VM/CT cloning

find-proxmox-macaddr-dups.pl

#!/usr/bin/perl

# string samples:
# /etc/pve/nodes/node1/lxc/123.conf:net0: name=eth0,bridge=vmbr0,firewall=1,gw=10.20.30.1,hwaddr=1A:2A:3A:CC:C0:0A,ip=10.20.30.40/24,type=veth
# /etc/pve/nodes/pm8/qemu-server/134.conf:net0: virtio=A1:B2:C3:B4:D5:E6,bridge=vmbr0,firewall=1

use strict;
use warnings;

open F, "grep -R hwaddr= /etc/pve |" or die "Cannot grep /etc/pve: $!\n";
my %mac2sys;
foreach(<F>) {
	next unless /\/(\d+)\.conf:([^:]+): .+,hwaddr=([^,]+),/
	         or /\/(\d+)\.conf:([^:]+): .*virtio=([^,]+),/;
	my ($vm, $iface, $macaddr) = ($1,$2,$3);
	my $a = ( $mac2sys{$macaddr} ||= {} );
	($a->{"$vm:$iface"} ||= 0)++;
}

foreach my $m (keys %mac2sys) {
	next if scalar keys %{$mac2sys{$m}} == 1;
	print "$m\n";
	print "\t$_\n" foreach keys %{$mac2sys{$m}};
}

## END ##