strange messages from -current 'dhcpcd'

["John D. Baker" <jdbaker%mylinuxisp.com@localhost>]

I've just noticed some strange log messages emitted by 'dhcpcd' on
-current (7.99.32).  I've seen these on i386, amd64, and evbarm-earmv7hf.

They are of the form:

Jun 18 12:56:53 hostname dhcpcd[PID]: wm0: invalid UDP packet from 19.100.192.168
Jun 18 12:56:53 hostname dhcpcd[PID]: wm0: invalid UDP packet from 20.12.192.168
Jun 18 14:15:22 hostname dhcpcd[PID]: wm0: invalid UDP packet from 119.16.192.168
Jun 23 21:48:35 hostname dhcpcd[PID]: wm0: invalid UDP packet from 150.129.192.168
Jun 23 18:57:32 hostname dhcpcd[PID]: wm0: invalid UDP packet from 163.85.192.168
Jun 24 02:56:29 hostname dhcpcd[PID]: wm0: invalid UDP packet from 76.24.192.168

Needless to say, the purported source IPs are not on my network.  My NAT
router blocks all incoming traffic except SSH, HTTP, HTTPS and those are
specifically redirected to hosts other than the ones from which the above
data were gathered.

It is curious how they all share the attribute that their last two octets
are the Class C private allocation prefix.

These same machines (and others), while running NetBSD-7.0_STABLE (amd64,
i386, sparc) with 'dhcpcd', have not exhibited such messages.

(Alas, there are some redmond-OS machines on my network--not by my
choice....)

I'm watching the interface with 'tcpdump' on one of the affected machines
to see if I can get more information.


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