Re: Kernel Level DHCP Versus udhcp

[Justin Carlson <justincarlson@cmu.edu>]

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On Fri, 2002-03-15 at 14:22, Abdij Bhat wrote:
> Hi,
>  I am deploying a Linux Network Stack. I am supposed to use a stable, fully
> featured, RFC compliant, small memory foot-print DHCP client for an embedded
> system. We had converged on udhcp for the client. But I have found that
> there is a DCHP client implemented in the Linux Kernel ( Version 2.2.x or
> later ). This I believe can be configured by choosing the "Kernel level
> autoconfiguration".
>  I have however practically no documentation on the Kernel DHCP Client. I do
> not know how buggy it is, is it a fully featured DHCP client or is it just a
> boot level DHCP client used for remote booting etc.
>  Can some body help me with this. I believe it is used only for the remote
> booting, with the documentation currently available to me. How correct am I?
> Can I replace the udhcp client with this one? How much of a change will I
> need to do for the replacement?

It sounds like the kernel DHCP client is not what you want.  It's really
intended for situations where you need to get dynamically assigned IP
information for a machine before you're far enough in the bootstrap to
do it in userland.

The most common situation for this that comes to mind is mounting your
root filesystem over NFS.  At least, that's the only situation for which
I've needed it.

If, as you imply, you really need a full-featured DHCP client, you
should be using something in userland.  The kernel-level one doesn't
(last I checked) handle DHCP details like temporarly IP address leases
and such; that's not the intention of having that option in the kernel.

-Justin


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