mysterious dhcpcd behaviour

[albright]

Hi all. I have a cable modem attached to a computer which serves
as router for my home network. My logs report that last night
something strange happened.

First:

[depontius]

It's possible that someone on your cable network is running a rogue DHCP server. Years ago when I first went cable, I ran into the same thing. Shortly later I had reason to talk to tech support, and found out that indeed there had been a rogue DHCP server on the segment. The reason to run a rogue server is so that they can own either your DNS lookups or all of your traffic. At that point, they could sift whatever they want to out of your traffic, for whatever information they want.

Quite frequently the cable company will run its infrastructure in IANA space, but from what I've seen they run it in the ClassA IANA - 10.x.x.x, not the ClassC 192.168.x.x. Back in the old days, when I ran a dual-homed bastion host right on the Internet, I could see the ID of my DHCP server, and it was normally on the 10.x.x.x network. But it assigned me a good, routable address, and my default route was in that same subnet.

AFAIK major ISPs all assign routable addresses. In this case, you have not been given one - you've been given an IANA address, and no doubt your default route is through one, also. I would disconnect, contact tech support, and NOT do anything significant on the Internet until you've sorted this out.
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.sigs waste space and bandwidth

[treefinger]

it is your internal NIC asking your what would be WAN nic if it would like an IP.

[Hu]