[Dnsmasq-discuss] Conditional sending of different DHCP-Options

Tue Aug 12 17:23:11 BST 2008

Hi !

I have the following setup here:
- DNSMasq 2.41 on an OpenWrt box. (192.168.137.1/wrt)
- A DBOX2 in Debug Mode I want to boot via BOOTP/DHCP/TFTP. (192.168.137.14)

The problem: The DBOX refuses to boot, because a certain file 'uboot.0'
is send twice.

On WRT dnsmasq is called in the following way:
/usr/sbin/dnsmasq -K -D -y -Z -b -E -s lan -S /lan/ -l
/var/cache/dhcp.leases -r /tmp/resolv.conf.auto
--dhcp-range=lan,192.168.137.34,192.168.137.63,255.255.255.0,12h -I ppp0

The file /etc/dnsmasq.conf constains the following:
## /etc/dnsmasq.conf
## user dns masq is running as
user=root
## log dns queries
#log-queries
## enable dhcp logging
log-dhcp
## tftp base
enable-tftp
tftp-root=/mnt/tftproot
#- default netboot
dhcp-boot=/tftpboot/pxelinux.0
#- i386 netboot
dhcp-boot=net:i386pxe,/tftpboot/pxelinux.0,wrt.lan,192.168.137.1
#- DBox2 netboot setup
dhcp-host=00:50:9c:12:34:56,bibu.lan,ignore
dhcp-boot=net:dbox2-uboot,/tftpboot/dbox/uboot.0,wrt.lan,192.168.137.1
dhcp-mac=dbox2-uboot,00:50:9c:*:*:*
# "DBOX2, EMPTY" is the complete string for yadi cdk-uboot,
# but dnsmasq searches for a substring
dhcp-boot=net:dbox2-kernel,/tftpboot/dbox/kernel,wrt.lan,192.168.137.1
#dhcp-vendorclass=dbox2-kernel,DBOX2, EMPTY
dhcp-vendorclass=dbox2-kernel,DBOX2

At first (stage1) the embedded bootloader of the DBOX2 request an IP +
some options eg. the bootfile uboot.0 via BOOTP.

Then (stage2) uboot.0 is started an request IP + bootoptions via DHCP.
The vendor class is "DBOX2, EMPTY" (obtained via tcpdump/wireshark) , so
the line
dhcp-vendorclass=dbox2-kernel,DBOX2
should match.

Here is the syslog extract:
Aug 12 18:08:51 wrt daemon.info dnsmasq[369]: Available DHCP range:
192.168.137.34 -- 192.168.137.63
Aug 12 18:08:51 wrt daemon.info dnsmasq[369]: next server: 192.168.137.1
Aug 12 18:08:51 wrt daemon.info dnsmasq[369]: bootfile name:
/tftpboot/dbox/uboot.0
Aug 12 18:08:51 wrt daemon.info dnsmasq[369]: server name: wrt.troja
Aug 12 18:08:51 wrt daemon.info dnsmasq[369]: BOOTP(br-lan)
192.168.137.14 00:50:9c:12:34:56
Aug 12 18:08:51 wrt daemon.info dnsmasq[369]: tags: lan, bootp, known,
dbox2-uboot
Aug 12 18:08:51 wrt daemon.info dnsmasq[369]: sent size:  4 option:
1:netmask  ff:ff:ff:00
Aug 12 18:08:51 wrt daemon.info dnsmasq[369]: sent size:  4 option:
28:broadcast  c0:a8:89:ff
Aug 12 18:08:51 wrt daemon.info dnsmasq[369]: sent size:  4 option:
3:router  c0:a8:89:01
Aug 12 18:08:51 wrt daemon.info dnsmasq[369]: sent size:  4 option:
6:dns-server  c0:a8:89:01
Aug 12 18:08:51 wrt daemon.info dnsmasq[369]: sent size:  5 option:
15:domain-name  74:72:6f:6a:61
Aug 12 18:08:51 wrt daemon.info dnsmasq[369]: sent size:  4 option:
12:hostname  62:69:62:75
Aug 12 18:08:52 wrt daemon.info dnsmasq[369]: TFTP sent
/mnt/tftproot/tftpboot/dbox/uboot.0 to 192.168.137.14
Aug 12 18:08:54 wrt daemon.info dnsmasq[369]: DHCP packet:
transaction-id is 827861916
Aug 12 18:08:54 wrt daemon.info dnsmasq[369]: Available DHCP range:
192.168.137.34 -- 192.168.137.63
Aug 12 18:08:54 wrt daemon.info dnsmasq[369]: DHCPDISCOVER(br-lan)
00:50:9c:12:34:56
Aug 12 18:08:54 wrt daemon.info dnsmasq[369]: DHCPOFFER(br-lan)
192.168.137.14 00:50:9c:12:34:56
Aug 12 18:08:54 wrt daemon.info dnsmasq[369]: next server: 192.168.137.1
Aug 12 18:08:54 wrt daemon.info dnsmasq[369]: bootfile name:
/tftpboot/dbox/uboot.0
Aug 12 18:08:54 wrt daemon.info dnsmasq[369]: server name: wrt.troja
Aug 12 18:08:54 wrt daemon.info dnsmasq[369]: tags: lan, known, dbox2-uboot
Aug 12 18:08:54 wrt daemon.info dnsmasq[369]: sent size:  1 option:
53:message-type  02
Aug 12 18:08:54 wrt daemon.info dnsmasq[369]: sent size:  4 option:
54:server-identifier  c0:a8:89:01
Aug 12 18:08:54 wrt daemon.info dnsmasq[369]: sent size:  4 option:
51:lease-time  00:00:a8:c0
Aug 12 18:08:54 wrt daemon.info dnsmasq[369]: sent size:  4 option:
58:T1  00:00:54:60
Aug 12 18:08:54 wrt daemon.info dnsmasq[369]: sent size:  4 option:
59:T2  00:00:93:a8
Aug 12 18:08:54 wrt daemon.info dnsmasq[369]: sent size:  4 option:
1:netmask  ff:ff:ff:00
Aug 12 18:08:54 wrt daemon.info dnsmasq[369]: sent size:  4 option:
28:broadcast  c0:a8:89:ff
Aug 12 18:08:54 wrt daemon.info dnsmasq[369]: sent size:  4 option:
3:router  c0:a8:89:01
Aug 12 18:08:54 wrt daemon.info dnsmasq[369]: sent size:  4 option:
6:dns-server  c0:a8:89:01
Aug 12 18:08:54 wrt daemon.info dnsmasq[369]: sent size:  5 option:
15:domain-name  74:72:6f:6a:61
Aug 12 18:08:54 wrt daemon.info dnsmasq[369]: sent size:  4 option:
12:hostname  62:69:62:75
Aug 12 18:08:54 wrt daemon.info dnsmasq[369]: DHCP packet:
transaction-id is 827861916
Aug 12 18:08:54 wrt daemon.info dnsmasq[369]: Available DHCP range:
192.168.137.34 -- 192.168.137.63
Aug 12 18:08:54 wrt daemon.info dnsmasq[369]: DHCPREQUEST(br-lan)
192.168.137.14 00:50:9c:12:34:56
Aug 12 18:08:54 wrt daemon.info dnsmasq[369]: DHCPACK(br-lan)
192.168.137.14 00:50:9c:12:34:56 bibu
Aug 12 18:08:54 wrt daemon.info dnsmasq[369]: next server: 192.168.137.1
Aug 12 18:08:54 wrt daemon.info dnsmasq[369]: bootfile name:
/tftpboot/dbox/uboot.0

The first autoconfiguration request is done via BOOTP, so I have no
chance to match on this.
The second request is as you can see in the done via DHCP. Wireshark
says there option 60 (vendor class) in the request with content "DBOX2,
EMTPY".
So the line
dhcp-vendorclass=dbox2-kernel,DBOX2
should match, but the boot file is still
/mnt/tftproot/tftpboot/dbox/uboot.0 instead of /tftpboot/dbox/kernel.

The pcap file I have omitted, yet, because I think all relevant facts
are in here. I can reproduce and make it avaiable for download if needed.

Do you have an hint where look in documentation, or what settings I can
try to solve this issue.

There has been a similar problem on this list, but it was not solved,
because the poster did not answer on the list [1]. Perhaps were now able
to solve it with more information provided.

kind regards
joerg jungermann

[1]
http://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2006q1/000651.html