XceptN’s IT Blog

While transmitting data in Urgent Mode  at the socket layer:

• Urgent mode is initiated using send(…, MSG_OOB),
• Current outgoing queue is longer than MTU
• Several packets are sent out with the URG flag set.

The Urgent Pointer field in the TCP header is not updated correctly. Instead, it stays the same. (more…)

I really do not like increasing the MTU that large..Some reasons below… (more…)

I have been referring to linlap for this configuration. The configuration has been made possible via ipw3945 and iwlwifi. To be more precise: (more…)

This is done by the boot paramer in vm.cfg.

The switches are:

* floppy (a)
* hard disk (c)
* Network (n)
* CD-ROM (d)

If you use

boot = ‘n’

it will be stuck at PXE boot even if there is no dhcp lease and guest will not attempt boot from the Virtual Disk.

To be able to have an order, you need to concatenate the switches. e.g. if you need to have a boot order like

1. network (n)
2. harddisk (c)
3. cdrom (d)

you need to have

boot=”ncd”

in vm.cfg.

Moreover,

If somehow the TFTP server is not accessible or misconfigured, that will fail
over to “c” aka. disk..

But if the DHCP server is not available, the boot will be stuck in a loop of “No
IP address”. Actually this is not much different from a normal BIOS.. A couple
of Dell systems with IBA (Intel Boot Agent) behaves similarly, but only
providing keystroke options.

I’ll also check the behaviour model of pypxeboot too ..

Configuring a PXE boot server

Install required packages:

# yum install bind dhcp system-config-netboot tftp-server

Setup dhcpd:

Copy the vmlinuz, initrd.img to /tftpboot/linux-install directory.

Create a default:

# cat /tftpboot/linux-install/pxelinux.cfg/default
timeout 100
default el5u1
prompt 1
display boot.msg
label el5u1
kernel vmlinuz
append initrd=initrd.img
#

Set the boot message:

Set disable=no in /etc/xinetd.d/tftp (enable tftp)

Setup the services:
# service xinetd restart
# service dhcpd restart
# touch /etc/named.conf
# service named restart
# service iptables stop (or allow tftp connection in the iptables config)