[Beowulf] OT: PXE boot with no control over DHCP?

Joe Landman landman at scalableinformatics.com
Thu Sep 22 12:04:36 PDT 2005

Hi David:

David Mathog wrote:
> On one workstation in the room in question (attached to the same
> switch as the PXE workstation) these commands were run:
>   /etc/rc.d/init.d/iptables stop
>   tcpdump -e -vv >foo.txt
> Then I tried a PXE boot on the second workstation.  After it
> timed out the log file was searched with:
>   grep -i '00:04:76:EF:AF:FA' foo.txt

Grep for DHCPDISCOVER in the /var/log/messages.  Do you see any?  Are 
you sure the dhcpd is up and running?

If you can convince yourself that

a) dhcpd is up and running,
b) is correctly configured
c) is listening to the right port
d) is not off in some odd state (ISC nahhhh  couldn't be....  )

then try a cross over cable if possible between the units.  If that 
works, and then you insert the switch back between the two, then the 
switch is in all likelyhood blocking UDP broadcasts (such as BOOTP/PXE 
type requests).  You need to then speak with the master of the switch, 
bring them burnt offerings, and other gifts, in order to get them to 
make the change.

If you don't get anything in your logs from this, do a sanity check with 
a laptop, a crossover cable, and make sure the dhcpd is working.

Note:  I usually turn off the ISC dhcpd and use dnsmasq, as I have a 
finite time to mess around with options, and the dnsmasq dhcp server 
(and pxe server for that matter) "just works"(tm).


Joseph Landman, Ph.D
Founder and CEO
Scalable Informatics LLC,
email: landman at scalableinformatics.com
web  : http://www.scalableinformatics.com
phone: +1 734 786 8423
fax  : +1 734 786 8452
cell : +1 734 612 4615

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