Mute "arp: 01:02:03:04:05:06 is multicast"; find source?

From: parv/freebsd <parv.0zero9+freebsd_at_gmail.com>
Date: Sun, 14 Nov 2021 22:40:56 UTC 
 Hi there,

Is there any way to mute in syslog message ...

arp: 01:02:03:04:05:06 is multicast

... or block|drop via some firewall rule? On some days it comes
nearly every hour, each instance shifted forwarded by few minutes ...

...
Nov 12 17:23:34 idas1 kernel: arp: 01:02:03:04:05:06 is multicast
Nov 12 18:25:22 idas1 kernel: arp: 01:02:03:04:05:06 is multicast
Nov 12 19:27:10 idas1 kernel: arp: 01:02:03:04:05:06 is multicast
Nov 12 20:28:58 idas1 kernel: arp: 01:02:03:04:05:06 is multicast
Nov 12 21:30:46 idas1 kernel: arp: 01:02:03:04:05:06 is multicast
Nov 12 22:32:34 idas1 kernel: arp: 01:02:03:04:05:06 is multicast
Nov 12 23:34:23 idas1 kernel: arp: 01:02:03:04:05:06 is multicast
Nov 13 00:36:11 idas1 kernel: arp: 01:02:03:04:05:06 is multicast
Nov 13 01:37:59 idas1 kernel: arp: 01:02:03:04:05:06 is multicast
Nov 13 02:39:47 idas1 kernel: arp: 01:02:03:04:05:06 is multicast
Nov 13 03:41:35 idas1 kernel: arp: 01:02:03:04:05:06 is multicast
Nov 13 04:43:23 idas1 kernel: arp: 01:02:03:04:05:06 is multicast
Nov 13 05:45:11 idas1 kernel: arp: 01:02:03:04:05:06 is multicast
Nov 13 06:46:59 idas1 kernel: arp: 01:02:03:04:05:06 is multicast
Nov 13 07:48:47 idas1 kernel: arp: 01:02:03:04:05:06 is multicast
Nov 13 08:50:35 idas1 kernel: arp: 01:02:03:04:05:06 is multicast
Nov 13 09:52:24 idas1 kernel: arp: 01:02:03:04:05:06 is multicast
Nov 13 10:54:12 idas1 kernel: arp: 01:02:03:04:05:06 is multicast
Nov 13 11:56:00 idas1 kernel: arp: 01:02:03:04:05:06 is multicast
Nov 13 12:57:48 idas1 kernel: arp: 01:02:03:04:05:06 is multicast
Nov 13 13:59:36 idas1 kernel: arp: 01:02:03:04:05:06 is multicast
Nov 13 15:01:24 idas1 kernel: arp: 01:02:03:04:05:06 is multicast
Nov 13 16:03:12 idas1 kernel: arp: 01:02:03:04:05:06 is multicast
Nov 13 17:05:00 idas1 kernel: arp: 01:02:03:04:05:06 is multicast
Nov 13 18:06:48 idas1 kernel: arp: 01:02:03:04:05:06 is multicast
...


On a FreeBSD 12.2 host, it just gets logged.
On a (FreeBSD) 13.0 host, message is logged and also sent in daily email.

Also, how could I identify the source that causes the message in the
first place?


- parv