Friday, December 23, 2005

DNS and the ActionTec Modem

he dhclient3 client runs /etc/dhcp3/dhclient-script can be extended by simply creating your own scripts under /etc/dhcp3/dhclient-*-hooks.d/. Check out the man pages for dhclient-script ($ man 8 dhclient-script) and read the HOOKS section.

What I did was just dropped the following script in as an exit hook, so it is executed after the /etc/resolv.conf is updated.

All this hack does is strip out the crap that really doesn't work anyways.

$ cat /etc/dhcp3/dhclient-exit-hooks.d/check_actiontec_dns
echo `date`: checking dns ordering for actiontec woes
grep ${BAD_IP} /etc/resolv.conf > /dev/null
if [ $? == 0 ]; then
echo removing actiontec dns entry
grep -v ${BAD_IP} /etc/resolv.conf > /tmp/resolv.conf
mv /tmp/resolv.conf /etc/resolv.conf

One thing that may break for you is if you go to another wifi access point that is NOT actiontec and it only has a single dns entry. If it did, then you'd end up with an empty /etc/resolv.conf file! Just use this script as a base....

Thursday, December 08, 2005

QEMU -- Likes and Dislikes

Here are some things I'm starting to notice about QEMU:

- Loading and saving state -- CTRL-ALT-2 and use loadvm and savevm
- Snapshots -- Use snapshot mode for when you are ready to do some major testing or upgrading. If all goes well, go to the console and commit changes.

- Clipboard integration b/w host and guest. Doesn't seem to be any at all.
- Mouse captured by the guest. Only way to get out is to hit CTRL-ALT. Minor, but I really liked the way VPC and VMWare integrated after you installed the add-ons.

1) $ qemu -localtime -user-net -m 384 -hda -smb /home/dbreese -loadvm tempsave winxppro.img
Could not open '/dev/kqemu' - QEMU acceleration layer not activated

To fix (
# /sbin/modprobe kqemu
# mknod /dev/kqemu c 250 0 # Create the KQEMU device
# chmod 666 /dev/kqemu # Make it accessible to all users

If modprobe gives error, then you may be able to:
# mkdir -p /lib/modules/$(uname -r)/misc && cp ~/qemu-0.7.2/kqemu/kqemu.ko /lib/modules/$(uname -r)/misc && depmod -a

Sometimes, you will need to insert another cd into the drive. The behaviour is not good for me because my host OS (Ubuntu running Gnome) grabs and mounts the drive. No matter what I tried (manually unmounting and remounting the drive, etc) I could not get QEMU to see the new disk which I had just inserted. To fix this, hit CTRL-ALT-2 in the guest and type:
qemu> change cdrom /dev/cdrom

And it will unmount and remount the cdrom within the guest.

Dual Boot Windows XP and Linux

I installed Linux first. I left the first partition for Windows. I installed Linux first and then installed Windows XP Pro.

1) Partition entire drive during linux install. I created the following partitions:
Partition 1 - ntfs - /dev/hda1 - 10gigs
Parittion 2 - ext3 - /dev/hda2 - I made this just a 512M /boot partition to contain my boot images and GRUB config.
Partition 3 - Logical Partition (LVM) - /dev/hda3 - containing 1 volume group with two volumes: home and root - 68 gigs
Partition 4 - Swap - /dev/hda4 - 2 gigs

The nice thing about using a logical volume is that it can be dynamically sized and resized over time. It supposedly does have a small performance hit, so for servers with lots of disk activity, it needs more investigation.

2) Install Linux.
Easy step.

3) Backup MBR
The MBR is stored on first 512 bytes of your primary drive. To back it up is really easy -- just use "dd". One word of caution, though -- make sure you back it up to a drive that is NOT a Logical Volume. That is, put it on a floppy (or your iPod as I did!). If you do, it is still possible to get it back, so don't worry.

$ dd if=/dev/hda of=/media/ipod/mymbr.bak count=1 bs=512

4) Install Windows.
When installing windows, choose the parition you want to install it on. I've heard Windows only really likes to be installed on /dev/hda1, so that is what I always stick to.

Windows will tromp your MBR, so it will only boot into Windows. No worries, though -- the partition table is still there and your data should be there, too!

5) Restore MBR because Windows is not nice and rewrites it.

To do this, I use Knoppix. Download it for free and burn a cd. You can use just about any bootable linux distro. Basically, it is linux which boots into a desktop with most of the common utilities ever needed. I've even used it as a diskless workstation before and used a 512meg pen drive as my home directory.

Once booted into Linux, just put in your floppy or mount your disk where you backed the MBR up to. Then restore the MBR:

$ mount -t ext3 /dev/hda2 /mnt/hda2 (this was my /boot partition was just an ext3 partition)
$ dd in=/mnt/hda2/mymbr.bak of=/dev/hda count=1 bs=512

Then reboot and you should be back into Linux.

6) Update GRUB to boot Windows.
Once back into your previously installed linux, edit /boot/grub/menu.lst and add the following to GRUB's config to optionally boot into Windows during power on:

title Microsoft Windows XP Pro
root (hd0,0)
chainloader +1

Other notes:
When I originally partitioned my /dev/hda1, I set the partition type to FAT32. However, when I installed XP, I formatted it as NTFS. When I did all of the above steps, Ubuntu would not load. It complaied during startup that /dev/hda1's partition type was incorrect and just hung. Seems like it should have continued, but it didn't. In /etc/fstab, I could probably add "errors=remount-ro" to /dev/hda1. Anyways, this is what I had to do to get things all fixed back up.

1) Boot into Knoppix
2) Install LVM support ( and mount your root partition (or wherever you have /etc mounted on).
3) vi /mnt/myoldroot/etc/fstab and comment out the entry for /dev/hda1
4) Once I was able to boot back into my Ubuntu system, I again edited /etc/fstab and changed the type to NTFS and did a "mount -a" to mount it and check it out.
5) To fsck the filesystem:
fsck -a /dev/VolGroup00/LogVol00 # took a long time

Other LVM links:
Channel #lvm on freenode


I've used VirtualPC, VMWare, and QEMU. QEMU (with KQEMU accelerator, which you don't want to do without). Here are some notes/issues/resolutions for each:

I use the VM's to connect to my corporate VPN via Nortel's Contivity client.

I also took a brief look at BOCHS, but didn't install it. It seemed that most www chater was all about QEMU.

VirtualPC 2005:
- Sometimes shared folders in the guest would "isolate" themselves and never update, even though the host had modified contents of the shared folders. This was a killer for me because I used the VM to do CVS version control within my VPN and my host as the development environment.
- Known issue was found for VirtualPC after applying service pack that stated VPC doesn't run well on laptops with my intel chipset (P4 Centrino w/ Mobile Technology. The "fix" from Microsoft just ran my PC at full blast to keep the chip from entering power saving modes.

- No complaints. Sometimes the mouse pointer gets hosed up and I have to switch from VM to HOST and back and it clears it up.
- Stable.
- Expensive ($180), which is the killer for me. No way will I remove that much out of my own pocket.
- Linux 2.6 time sync issue (documented below)
- Wireless networking can only use NAT. Appearantly an issue with the Linux drivers, not with VMWare.

- Just installed it on my Linux 2.6 Ubuntu.
- Compiled it from source along with the kqemu performance package.
- First issue -- mouse integration did not work. Solution: export SDL_VIDEO_X11_DGAMOUSE=0 before starting qemu.
- Networking ran out of the box.
- Linux 2.6 time sync issue (documented below)
- As with VMWare, you can only use NAT due to limitation in the Linux drivers.
- Once I get around to configuring my guest to connect to my corporate VPN, I will be very curious to know if/how folder sharing works.
- NAT networking is pretty slick -- it has its own firewall, dns, and dhcp.

Here's my startup script for QEMU:
$ cat
qemu -localtime -user-net -m 384 -hda winxppro.img

Linux 2.6 Time/Clock Synchronization issue
I've installed the 2.6 (i686) kernel. Appearantly a setting in the Linux source changed from 2.4 to 2.6 which affects the way a virtual machine keeps up with the correct time. The effect was that the guest's clock ran up to 10x warp speed. You could see this by launching the XP Clock.

This issue mostly seems appearant in Mobile chipsets, not desktops, but I'm not 100% sure. The only way I could fix it was by passing "acpi=off" to my kernel during boot. My GRUB /boot/grub/menu.lst entry looks like this:
title Ubuntu, kernel 2.6.12-10-686 (VM TRIALS)
root (hd0,1)
kernel /vmlinuz-2.6.12-10-686 acpi=off root=/dev/mapper/ubuntuvg-root ro quiet splash
initrd /initrd.img-2.6.12-10-686

Now my guest clocks stay in perfect sync. However, power saving features are disabled, which is a bugger.

SIMP for Linux

I've used SimpLite ( for MSN encryption for conversations.
Since I'm running Ubuntu now, I found that Secway also has a Linux

Simply download, extract to /usr/local/simp and start it up. By
default, it starts a local socks-4 proxy for MSN on port 11863, so you
have to configure GAIM to use that port.

Unlike the Windows client, the server version of SIMP must automatically
create keys for you because I didn't have to do anything.

I created an init.d script as follows to auto start/stop it:

#! /bin/sh


set -e

case "$1" in
if [ -e $PIDFILE ]; then
echo $PIDFILE already exists, not starting server.
exit 1
nohup $SIMPSERVER >/dev/null 2>&1 &
echo $! > $PIDFILE
kill -TERM $(cat $PIDFILE)
echo $1 not implemented. just kill and restart it yourself.
echo "Usage: $N {start|stop|restart|force-reload}" >&2
exit 1

exit 0

Ubuntu and Debian Packages

Since Ubuntu is a take-off from Debian, it naturally uses Debians packaging tools such as apt-get, to update and configure your system. You may also use the GUI tool, Synaptics Package Manager.

Here are some useful links and info:
Good info about packages (see CONTENTS for a lot more on using apt* tools):

Update all installed packages:
# apt-get update

Install a package:
# apt-get install some-pkg

See what's installed:
# dpkg -l | more

Query packages:
# apt-cache search someRE*

You can convert an RPM file to a DEB package (or to/from other common formats) by using Alien:
$ alien --to-deb somefile.rpm (will create somefile.deb)

Some other things to mention -- apt* tools use a local "database" to drive what packages are available and where to get them. Read the URL link above to understand how it works and how to keep it up-to-date so you always know what the latest packages are available.

Ubuntu Linux 5.10

Running Ubuntu (Breezy Badger) 5.10 linux on laptop now. So far, it is great. Only thing I had issues with was my display driver. I have an HP/Compaw nw8240 latop with an ATI FireGL v5000 card. I had to go and download the linux drivers directly from ATI's website and install them and all is well now.

I downloaded version 8.19.10. (

The GL graphics are very slow (screen savers and most games are extremely slow in repainting the screen), but other graphics such as window movements, etc are very fast.

Need to work on DRI support. Supposedly it gives better results.

VERY IMPORTANT NOTE: I installed KDE and X went back to the flashy screen. Even reinstalling the ATI drivers didn't work. Finally found a configuration utility installed by ATI under /usr/X11R6/bin/fglrxconfig which recreates the xorg.conf file and everything will work!