[Dnsmasq-discuss] what is 'next-server' ? is it dhcp-option 66?

[Geert Stappers]

On Sat, Jun 26, 2021 at 09:55:01AM +0700, Bino Oetomo wrote:
> Dear All.

Hello,

 
> I have 3 Virtualbox guest.
> A. tftp-server DNSMASQ v.2.80 with IP address 10.10.254.1
> B. dhcp-server DNSMASQ v.280 with IP address 10.10.254.2 and 10.10.253.1 (This one facing IPXE client)
> C. IPXE client

<monospaced_font_required example_given="dnsmasq mailinglist archive">


+-----+                   +-----+                   +-----+
|     |    10.10.254      |     |     10.10.253     |     |
|  A  +-------------------+  B  +-------------------+  C  |
|     |.1               .2|     |.1            .dhcp|     |
+-----+                   +-----+                   +-----+

</monospaced_font_required>
 
> When I config dhcp server with:
> 'dhcp-boot=lpxelinux.0,server.name,10.10.254.1'
> IPXE client received 'next server' 10.10.254.1
> 
> Next try, I commented 'dhcp-boot' line, and put
> dhcp-option=66,10.10.254.1
> dhcp-option=67,lpxelinux.0
> 
> DNSMASQ log says:
> 
> dnsmasq-dhcp: 3891074361 next server: 10.10.253.1
> dnsmasq-dhcp: 3891074361 sent size:  1 option: 53 message-type  5
> dnsmasq-dhcp: 3891074361 sent size:  4 option: 54 server-identifier 10.10.253.1
> dnsmasq-dhcp: 3891074361 sent size:  4 option: 51 lease-time  12h
> dnsmasq-dhcp: 3891074361 sent size:  4 option: 58 T1  6h
> dnsmasq-dhcp: 3891074361 sent size:  4 option: 59 T2  10h30m
> dnsmasq-dhcp: 3891074361 sent size:  4 option:  1 netmask  255.255.255.0
> dnsmasq-dhcp: 3891074361 sent size:  4 option: 28 broadcast  10.10.253.255
> dnsmasq-dhcp: 3891074361 sent size:  4 option:  3 router  10.10.253.1
> dnsmasq-dhcp: 3891074361 sent size: 12 option: 67 bootfile-name  lpxelinux.0
> dnsmasq-dhcp: 3891074361 sent size: 12 option: 66 tftp-server  10.10.254.1
> 
> and the IPXE client receive 10.10.253.1, not as described by option:66

Come again, because I do see

 > dnsmasq-dhcp: 3891074361 next server: 10.10.253.1
 > dnsmasq-dhcp: 3891074361 sent size: 12 option: 66 tftp-server  10.10.254.1
 


> Is 'next-server' different from dhcp-option-66?

Yes, they are two different "fields" in a DHCP network packet.


Regards
Geert Stappers
Did invest yesterday (in his timezone) a lot of time
in an interesting DHCPrelay related problem.
-- 
Silence is hard to parse