[K12OSN] DHCP and different LTSP distros

Krsnendu dasa krsnendu108 at gmail.com
Wed Jul 11 02:35:46 UTC 2007

On 29/06/07, William Fragakis <william at fragakis.com> wrote:
> Tweaks for servers serving older PCs:
> If the PC, while PXE booting fails to get further than grabbing an IP
> address or begin tftp, you likely an older PXE firmware (0.99) that
> requires certain tweaks. Newer clients do not require these steps but it
> doesn't hurt to do them to facilitate easy swapping of clients later.
> We've only found this to be an issue with PII 350 and 400 Compaq
> DeskPros.
> Open the computer -> filesystem -> /etc
> open file /etc/sysctl.conf (it should open with Gedit or Kedit) append
> the file with the following (Include the # sign! It denotes a comment
> which is for human eyes and for the server to ignore. Well commented
> files make things easy for those who follow you.)
> # Disable MTU discovery for older PXE NICs (0.99)
> net.ipv4.ip_no_pmtu_disc = 1
> save the file and close
> next, open file /etc/xinetd.d/tftp
> change this line:
> server.args = -s /tftpboot
> to:
> server.args = -r blksize -s /tftpboot
> save the file and close (essentially, you are adding the -r blksize
> parameter). This change unlike any others will not be effective until
> you reboot the server. This is the only change that requires a reboot
> since it is kernel level. All other changes are package or service level
> and only require restarting that application or service.

I tried these settings, and now I get this message from tail -f
/var/log/messages when I start dhcpd and none of the clients can boot
from this server. Wen I start dhcpd on the secondary server the
terminals are able to boot from there.

Jul 11 14:27:36 k12ltsp2 dhcpd: Failover CONNECT from
time offset too large
Jul 11 14:27:36 k12ltsp2 dhcpd: failover: disconnect: time offset too large
Jul 11 14:27:36 k12ltsp2 dhcpd: dhcpd startup succeeded
Jul 11 14:27:51 k12ltsp2 dhcpd: failover peer ltsp: I move from
startup to communications-interrupted
Jul 11 14:27:51 k12ltsp2 dhcpd: failover: link startup timeout

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