di-netboot-assistant : DHCP server configuration
Hello,
I'm considering to add the paragraph below in di-netboot-assistant's
README.Debian file.
The second scenario is obviously a hack, but it could be useful for many
home users which have little control over their DSL modem's built-in
DHCP.
Typical implementation would use the following tips :
dnsmasq :
> dhcp-range=vendor:PXEClient,192.168.0.81,192.168.0.91
or dhcpd :
> if substring (option vendor-class-identifier, 0, 9) = "PXEClient" ...
I would like to get your opinion on this.
Thanks,
Franklin
### README.Debian snippet ###
DHCP SERVER
There are two typical scenarios:
+--------+
___ | Switch | +-------------------+
__/ \__ +--------+ | This host |
/ \ +--------------+ | | | | is the only |
( Internet )---| (DSL) Modem +----+ | +----| DHCP server |
\__ __/ | or router | | +-------------------+
\___/ +--------------+ | +-------------------+
+----| A client computer |
+-------------------+
> First case: This host is already the DHCP server for the local network.
This is the best and recommended configuration. You simply
have to add some options to enable netbooting (typically,
the "filename" to boot, and the tftp server's address).
+--------+
___ | Switch |
__/ \__ +---------------+ +--------+
/ \ | (DSL) Modem | | | | +-------------------+
( Internet )---| with +----+ | +----| This host |
\__ __/ | build-in DHCP | | +-------------------+
\___/ +---------------+ | +-------------------+
+----| A client computer |
+-------------------+
> Second case: A DHCP already exists, but you can't/don't want to use it
for netbooting. This isn't the recommended configuration,
but it was successfully tested for netbooting PXE clients
(i386, amd64 and ia64) on network where the existing DHCP
server didn't provide netboot informations.
!!! Do not setup rogue dhcp servers !!!
In this situation, you have to(1) divide your DHCP subnet in
two ranges of IP address. The first range will still be
served by the existing DHCP server.
The second part will be served by "this host". It will only
reply to DHCP request sent during PXE netboot step. This is
possible because client computers (actually, it's PXE agent
in the NIC's ROM) sends an option like this during PXE boot:
vendor-class= "PXEClient:Arch:00000:UNDI:002001"
Both dhcpd and dnsmasq can be instructed to provide answer
depending on such strings.
(1) For easy _home_ setup, you can choose not to reduce the
range of IP served by the existing DHCP server, and just
declare a small range of addresses, on both DHCP (some
addresses that are unlikely to be used on the first one)
That's ugly, but it can work ! (as long your existing DHCP
don't allocate some of those IP)
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