[ale] re: mediaone dhcp problem

Jacob Langseth jlangseth at vodavi-ct.com
Thu Aug 19 14:50:37 EDT 1999


> >Can you plug the cable modem interface into the
> >internal Lan, ifconfig the address properly and
> >successfully talk to the internal machines?
> 
> Yes.

Okay, the arp request is legit, ruling out your
ethernet card.  I'm somewhat at a loss as to why
an arp reply would be granted the service laptop
and not your system (unless there is actually an
issue with your system); to my knowledge media-
one does not hard code the macs.

> >If it works this way, it may be an obscure configuration
> >issue relating to your firewall, though from the original
> >email it didn't sound as if you had changed the configuration
> >recently.  Make sure ipfwadm -c accepts the arp reply
> >properly.
> 
> Didn't.  IPCHAINS, not IPFWDADM.  Hmmm.  

Both use the ipfw(4) kernel interface, so ipfwadm -c
should work.

> >Something else to try while your poking around, though I
> >don't know why it would make any kind of a difference,
> >would be to force feed the MAC address of the gateway
> >as received by the laptop into your arp table via arp -s;
> >it be interesting if it the connection started working.
> 
> Soon as I replace the nic in my own laptop (the service droid is long gone).

Shouldn't be necessary.  Tcpdump -e the dhcp reply.  The
nature of mediaone's network (last time I checked) is such
that the source mac in the reply will not be that of the dhcp
server, but that of the gateway, the purpose being to prevent
mac discovery of other hosts on the subnet (a Good Thing).
Try using the source mac from the dhcp reply in the arp -s
command.

Good luck.  My hunch is with ipfwadm -c...

Jacob

--	     	   	   	       		    	  		 
Jacob Langseth  	      
http://www.vodavi.com/	<jlangseth at vodavi-ct.com>






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