On 11/19/2012 1:23 PM, John Hupp wrote:
I had a thread named "LTSP-PNP on Lubuntu: Chromium
ERR_NAME_RESOLUTION_FAILED," but am starting a new thread to
accurately reflect the problem I'm now wrestling with.
I'm trying to troubleshoot an LTSP (the new LTSP-PNP) client boot
problem under Quantal. I installed with a single NIC per
https://help.ubuntu.com/community/UbuntuLTSP/ltsp-pnp
The problem is that the LTSP client, after successfully getting DHCP
assignments, fails to download the pxelinux boot image. It reports
"PXE-E32: TFTP open timeout."
To be more specific on the DHCP assignments, it identifies my hardware
router as the DHCP server and the default gateway. It identifies the
LTSP server as proxy and boot server.
I can also run this on the server itself to get a similar failure:
$ cd /tmp
$ tftp 192.168.1.102 -v -m binary -c get /ltsp/i386/pxelinux.0
mode set to octet
Connected to 192.168.1.102 (192.168.1.102), port 69
getting from 192.168.1.102:/var/lib/tftpboot/ltsp/i386/pxelinux.0 to
pxelinux.0 [octet]
Transfer timed out.
A CRITICAL NOTE: This is using the default network-manager to
configure the network interface (using the default DHCP configuration,
and the connection is "Available to all users"). Apparently
network-manager also runs or works with dnsmasq, which provide DHCP
and TFTP servers.
When I had TFTP and DHCP errors booting the client under LTSP5 and
Precise, I learned that the usual work-around was to configure the
network interface(s) via /etc/network/interfaces. I think this solved
some sort of a timing problem with the relevant services during bootup.
But that approach is apparently deprecated under Quantal and
LTSP-PNP. In fact, I can use that approach to get the client to boot
successfully, but it introduces a new problem on server and client:
DNS resolution fails. I understand that this happens because a
non-default /etc/network/interfaces causes ifupdown to configure
network interfaces instead of network-manager, but now network-manager
is being relied upon to provide DNS resolution with dnsmasq.
I can fix the DNS resolution problem by creating
/etc/resolvconf/resolv.conf.d/tail with contents:
nameserver (my nameserver 1)
nameserver (my nameserver 2)
-----------------------
But instead of patching up the old approach, I'd like to get the new
approach working right.
Looking for others who have dealt with the same problem, I have not
found much, but there was this 2010 thread:
http://ubuntuforums.org/showthread.php?t=1503710
One of the posters (#6) says that when he disabled NAT, TFTP started
working. I don't know what that means for me in my setup. But it did
get me to thinking about my little network running from my
consumer-class hardware router. Is dnsmasq in conflict with a service
being provided by the router? Is my router's firewall blocking FTP
communication between LTSP client and server?
If those are fruitless questions, then I would wonder why TFTP works
when I use /etc/network/interfaces and ifupdown to configure the
network interface, and it fails when network-manager governs instead.
By the way, this installation has seen very little modification. I
installed Quantal on a newly-formatted hard drive, allowing it to use
its default partitioning. I installed LTSP-PNP. I set up a scanner
via already-installed SANE. Also apcupsd for the sake of use with a
UPS. I installed HPLIP and an HP Laserjet printer.
-----------------------------
My (as-installed default) ltsp-server-dnsmasq.conf in case that is of
interest:
# Configures dnsmasq for PXE client booting.
# All the files in /etc/dnsmasq.d/ override the main dnsmasq
configuration in
# /etc/dnsmasq.conf.
# You may modify this file to suit your needs, or create new ones in
dnsmasq.d/.
# Log lots of extra information about DHCP transactions.
#log-dhcp
# IP ranges to hand out.
dhcp-range=192.168.67.20,192.168.67.250,8h
# If another DHCP server is present on the network, you may use a
proxy range
# instead. This makes dnsmasq provide boot information but not IP leases.
# (needs dnsmasq 2.48+)
dhcp-range=192.168.1.0,proxy
# The rootpath option is used by both NFS and NBD.
dhcp-option=17,/opt/ltsp/i386
# Define common netboot types.
dhcp-vendorclass=etherboot,Etherboot
dhcp-vendorclass=pxe,PXEClient
dhcp-vendorclass=ltsp,"Linux ipconfig"
# Set the boot filename depending on the client vendor identifier.
# The boot filename is relative to tftp-root.
dhcp-boot=net:pxe,/ltsp/i386/pxelinux.0
dhcp-boot=net:etherboot,/ltsp/i386/nbi.img
dhcp-boot=net:ltsp,/ltsp/i386/lts.conf
# Kill multicast.
dhcp-option=vendor:pxe,6,2b
# Disable re-use of the DHCP servername and filename fields as extra
# option space. That's to avoid confusing some old or broken DHCP clients.
dhcp-no-override
# We don't want a PXE menu since we're using a graphical PXELinux menu.
#pxe-prompt="Press F8 for boot menu", 3
# The known types are x86PC, PC98, IA64_EFI, Alpha, Arc_x86,
# Intel_Lean_Client, IA32_EFI, BC_EFI, Xscale_EFI and X86-64_EFI
pxe-service=X86PC, "Boot from network", /ltsp/i386/pxelinux
# A boot service type of 0 is special, and will abort the
# net boot procedure and continue booting from local media.
#pxe-service=X86PC, "Boot from local hard disk", 0
# Comment the following to disable the TFTP server functionality of
dnsmasq.
enable-tftp
# The TFTP directory. Sometimes /srv/tftp is used instead.
tftp-root=/var/lib/tftpboot/
# Disable the DNS server functionality of dnsmasq by setting port=0
port=0
# Don't listen on lo, to prevent conflicts with Ubuntu's local
resolver hack (LP: #959037).
#except-interface=lo
#bind-interfaces
Trying to make some further progress on this, I have been looking at the
dnsmasq man page (it's big!).
It seems to me that I need to get into position to examine whether
dnsmasq started up with the right configuration. Does LTSP-PNP start
its own instance of dnsmasq? If so, can I restart that particular
instance, and where does it launch from?
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