IP get via Etherboot and IP get dhcpcd

Eric W. Biederman ebiederman at lnxi.com
Wed Feb 25 21:25:00 CET 2004

Peter Stuge <stuge-linuxbios at cdy.org> writes:

> On Wed, Feb 25, 2004 at 05:10:44PM -0800, YhLu wrote:
> > Eric,
> > 
> > I put the the dhcpcd in the initrd. After boot system with LinuxBIOS +
> > Etherboot + elf ( with the initrd). I found the IP got by Etherboot and
> > dhcpcd is different.
> > 
> > I may only used fixed option in dhcpd.conf to make it get the same addr?

If you specify the mac address and a fixed ip address you should always get the same IP.

> One explanation would be that Etherboot uses BOOTP while dhcpcd uses DHCP.
> Try making Etherboot speak DHCP as well.
> Otherwise maybe you can set up a fake dhcpcd-eth*.info file with the IP,
> but I doubt dhcpd will approve the request for that same address unless
> you use a really short lease time.

There are a couple of other possibilities.

dhcpcd is a broken client and can be fooled into thinking a reply to
another client is for itself as it does not verify the dhcp reply
it uses has the mac address it is requesting an ip address for.

dhclient works correctly and is strongly configurable.  I think
busybox also includes a working dhcp client.

Etherboot filters dhcp replies looking for a filename so it will
have something to boot from.  If you have 2 dhcp servers answering
you that could explain the difference.

packet sniffers like tcpdump and ethreal are your friends, as well
as log files in /var/log/


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