Re: dhcpdump not seeing dhclient messages
On Mon, Aug 26, 2013 at 01:28:44PM -0300, Luther Blissett wrote:
> I do not know if this is the case, but ISP's usually record its
> customers MAC address which is universally unique. Maybe, just maybe,
> when you switched from your tp-link router to direct wan link, the ISP
> machine noticed that there was an unknown MAC attempting to connect and
> refused connection. Then your dhcp discover packets would reach ISP
> hardware, but would not receive any responses.
I've checked with my ISP and they say to just power down the cable modem for 30
seconds before attaching a machine with a new MAC. And, I've been able to
switch between two other machines, both with different MAC addresses. It's just
this third machine that's given me problems.
What I'm really stuck on right now is why does the dhclient log show that it's
sending DHCPDISCOVER messages, but dhcpdump isn't seeing them? It's like
something is sitting between dhclient and my NIC. I've disabled all firewall
rules, though, so know it's not that. (All tables and chains have a default
policy of ACCEPT, and no rules.)
> BTW, you should notice that dchp communications are not held with the
> same machines when you have a direct link as opposed to routed link.
> When routed through some gateway, you have two sets of dhcp ISP <-->
> router <--> pc.
Thanks. All my connections right now are direct, like this:
[ISP]---[cable modem]---[my machine]
The cable modem is just a modem, and not a router.
But I know what you mean. My final configuration will be:
[ISP]---[cable modem]---[my machine, a router]---[LAN machines]
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