RND(tech)

LaCie brings Lightscribe to the rest of us

nospam@example.com (Khanh Tran) — Tue, 17 Oct 2006 15:16:33 -0700

LaCie announced today that they now offer a complete Lightscribe solution for all platforms. That means now Mac OS X and even Linux users can write labels to Lightscribe media with Lightscribe drives. Lightscribe is a technology that allows you to etch silk screen quality images on the label side of CD/DVD media. Up until now, the technology was limited to Windows users due to lack of software. Now with the LaCie LightScribe Labeler for MAC OS, SureThing for Windows and LaCie LightScribe Labeler for Linux, we have software available to the three major OS platforms. Did I forget to mention the software is free from LaCie? Yes, it really is.

See:
http://www.lacie.com/lightscribe http://www.lightscribe.com

using openSSH as a layer-2 ethernet bridge (VPN)

nospam@example.com (Khanh Tran) — Tue, 18 Nov 2008 21:11:40 -0700

Consider the following network setup (which I live with by the way):

[main LAN] <-----------------------------------------------------> [remote datacenter LAN]
(192.168.0.0/16) <-------- leased point-to-point ------------> (192.168.0.0/16)

Both locations also have separate connections to the public Internet with different public IP subnets. However, for this discussion it's not necessary to have different public IP subnets. Under normal circumstances the local LAN and the remote LAN are the same logical LAN via the magic of the leased point to point line.

However, today that p2p connection broke (physically between the two locations, out of our control). This outage lasted several hours, but brought out an interesting use of SSH tunneling for ethernet bridging aka Layer-2 VPN or tunneling. For this to work, you'll need to have at least openSSH 4.3, a somewhat recent linux distro and the bridge-utils package for your distro. This also assumes you have a basic knowledge of IP and the linux command line. I use openSuSE 11.0, but this should work for almost any similar linux.

Let's say for example, the main location has a linux box (router1) with two NICs:
eth0: 1.1.1.1 (the public interface)
eth1: unassigned IP, but connected to your LAN (192.168.0.0/16 in my case)

On the other box, at the remote location (router2) we also have two NICs:
eth0: 2.2.2.2 (the public interface)
eth1: unassigned IP, but connected to your LAN (192.168.0.0/16 in my case)

Both routers should be set with it's public IP gateway as the default route, working DNS, etc. You'll want to enable IP forwarding (consult your specific distro) and in my case, I disabled the distro's firewall. On the remote side (consider it the "server"), you'll need to edit your sshd config to allow remote root logins and tunnels via SSH.

/etc/ssh/sshd_config:
PermitRootLogin yes
PermitTunnel yes

The root login is necessary to allow ssh to create the TAP devices for the bridge. Because of that, you'll also want to add your local side's IPs to /etc/hosts.allow for the sshd process. Now, on the local side (IP 1.1.1.1, which you might consider the client now) you'll want to "su root" and do the following:

ssh -o Tunnel=ethernet -f -w 0:0 2.2.2.2 true

The -o switch sets client options on the command line. We're specifying the tunnel type as ethernet (bridge) as opposed to point-to-point, which it'll do by default (for Layer-3 type VPN routing). The -f switch just forks ssh in the background so we're returned to our "client's" command line and not remote's. Since we've done that, ssh will expect a remote command of some kind, so we'll just run "true", effectively doing nothing. The -w 0:0 switch actually sets up our tap devices on either side as tap0. You can do -w 1:1 for tap1, -w 0:1 for tap0 on one side and tap1 on the other, etc.

On both sides now, you should be able to see via ifconfig -a your eth0, eth1 and tap0 devices. Make sure to call ifconfig with -a, or you'll only see interfaces with defined IPs. Now that the two boxes are connected via the public Internet to each other via SSH, you can finally start to establish the bridge interface. Now we'll use the bridge-utils binary to create a bridge interface called br0:

brctl addbr br0
brctl addif br0 eth1
brctl addif br0 tap0

Then you'll want to bring up all of your interfaces, if they aren't already:

ifconfig eth1 up
ifconfig tap0 up
ifconfig br0 up

Doing so will create the br0 interface, then bridge your eth1 and tap0 together and bring up the interfaces. Don't forget, YOU MUST RUN THE brctl and ifconfig COMANDS ON BOTH SIDES!!! Once you've done this, you can check the remote side to see if it knows about the MAC addresses (from Layer-2) on the local side:

brctl showmacs br0

This will report on the known MAC address from the ARP protocol. Depending on your network, you'll see a few or many. Depending on your setup, you can get a DHCP address on the "other side" of the tunnel now or configure an appropriate IP and ping across as if you were on the same physical broadcast domain!

As a final note, there's always a downside. TCP encapsulated TCP is bad and will put a STRAIN on your hardware. Make sure it's decent for the amount of anticipated traffic and use only as a quick and dirty solution or a temporary measure. The following is good reading for why this is not a long-term, permanent solution:
http://sites.inka.de/~W1011/devel/tcp-tcp.html

Star Wars Coffee!

nospam@example.com (Khanh Tran) — Fri, 21 Nov 2008 09:40:09 -0700

Star Wars mugs always make coffee taste good!

Finished Final Fantasy IV Again!

nospam@example.com (Khanh Tran) — Sun, 11 Jan 2009 16:03:49 -0700

If you don't keep up with the blog, I've been re-living the Final Fantasy saga again. I've been playing them in order, and depending on how I feel after Final Fantasy VIII, I may stop or go on to Final Fantasy IX.

In any event, it took me nearly a year of on-again-off-again playing (totaling just under 43 hours of game time):

This story was one of my favorites too. Final Fantasy IV (orginally released as Final Fantasy II on SNES in America) was the first to have all of the original elements of the Final Fantasy we know and love. It's the five-member party, the near-active battle system, classic music, summons, fat chocobo, etc. Yes, and this is the one where you go to the moon. Contrary to popular belief, you don't have to have a level 70 party to complete it. I was fine with my mid-60 level party. Of course, higher would have helped more, but you can defeat Zeromus just fine. As you can see, in addition to Cecil, I brought along Palom, Porom, Cid, and Yang. Yang just uses his "power" for double attacks. Cecil just attacks since his white mage curaga is useless for healing even one person on a turn. Which means, you'll rely on Porom's more powerful curaja or full-life (instead of wasting a turn on a phoenix down, then curing). Next to Yang's attack, Cid's standard attack was important. Cecil is still fairly weak comparatively in the attack department. He's your standard RPG main character (who's always a knight or a fighter) so you have no choice but to bring him along in this case. The majority of your attack will be dealt by Palom. You could have brough Rydia and her summonses, but whatever. Palom has meteor which is probably just as powerful, although not as pretty to watch. Palom will hit for 9999 hit points, but your party will be countered with similar magic from Zeromus. Watch out for that Big Bang attack of his!

Now on to Final Fantasy V!

eh, wordle...

nospam@example.com (Khanh Tran) — Wed, 04 Feb 2009 11:36:47 -0700

Wordle generated and interesting graphic of the blog today...

If you look at it hard enough, it's slightly 3D!

Then there was this, more relaxed graphic:

Super Mario Bros Fish Tank

nospam@example.com (Khanh Tran) — Sun, 08 Feb 2009 20:42:44 -0700

Well, not quite totally a Mario Bros fish tank. However, I think the backdrop I made came out awesome.

AT&T 3G Speed tests

nospam@example.com (Khanh Tran) — Sun, 22 Mar 2009 12:33:22 -0700

I haven't been writing much lately due to a busy schedule!

Anyway, I recently borrowed one of those AT&T 3G LaptopConnect cards. It's a Sierra Wireless AirCard 881. Compared to the speeds I've been getting with my AT&T Tilt (tethered via USB), it didn't hold up as well as I expected:

AT&T Tilt (HTC) tethered via USB:

AT&T Sierra Wireless LaptopConnect Card (AirCard 881):

And although this isn't really for comparison to the AT&T test, it seems Cablevision (Optimum Online) has been steadily increasing my bandwidth at home, even out in the middle of nowhere!

burning files larger than 4GB with linux!

nospam@example.com (Khanh Tran) — Fri, 01 May 2009 19:51:18 -0700

Burning files larger than 4GB seems to be a tricky thing in most programs. Lets say for example, you have a DV file that's 6GB. You should be able to fit it on a dual layer DVD without issue, but most burning programs fail to handle it.

Linux seems to work wonders for me on the command line. If I figure out something in Mac or Windows, I'll let you know, but I don't have access to a dual layer burner on either of those OSes at this time.

In Linux, you can make the appropriate ISO image with either:

mkisofs -r -R -J -l -allow-limited-size -udf -o largefile.iso largefile.ext

or use:

genisoimage -allow-limited-size -udf -o largefile.iso largefile.ext

Once the ISO is generated, you could burn with growisofs -Z /dev/dvd=largefile.iso or move the ISO to Mac or Windows...

enabling OS X screen sharing remotely in Terminal

nospam@example.com (Khanh Tran) — Thu, 08 Oct 2009 19:40:56 -0700

short and simple for 10.5 (Leopard)

sudo sh -c "/bin/echo -n enabled > /Library/Preferences/com.apple.ScreenSharing.launchd"

slightly different for 10.6 (Snow Leopard)

sudo sh -c "/bin/echo -n enabled > /private/etc/ScreenSharing.launchd"

rm the file to disable it. launchd polls regularyly, so after you "enable" the service, it'll be loaded by the time you check for the open port with netstat -an

disabling NetBIOS over TCP/IP in Windows via BIND DHCPD

nospam@example.com (Khanh Tran) — Thu, 27 May 2010 08:31:40 -0700

This is scarce information on the Internet, so I'm reposting!

NetBIOS can be disabled now that it's fairly ancient networking. You're using TCP/IP and DNS right?
I don't use Microsoft DHCP or DNS servers, so finding the information to set this is hard to come by. To disable NetBIOS over TCP/IP in an ISC DHCP server, add the following to your dhcpd.conf:

option vendor-encapsulated-options 01:04:00:00:00:02;

It's that easy!

Exchange PowerShell script to sync contacts in an OU with a CSV file

nospam@example.com (Khanh Tran) — Fri, 11 Mar 2011 10:37:00 -0700

This was an extremely difficult topic to find information on, but very easy to write in Windows PowerShell. It seems a lot of others are syncing contacts in OUs across forests for multi-company organizations or similar. In my case, I'm the email admin at a college and need to populate contacts in our Exchange GAL from a CSV file. We use CSV imports due to the fact that we use multiple mail platforms and export address information from our ERP/SIS system for students.

My old process was to use CSVDE to import the CSV file into the ActiveDirectory OU "Students". However, this process required that I delete all 1,800 or so contacts and then reimport. This was not very elegant. So, after a lot of fruitless searching, I decided to write this script to handle our Student OU that contains only contact objects for the Exchange GAL.

This script first checks the existing contacts, based on email address, against the CSV file. If they exist in the file, great, do nothing, otherwise, delete the contact in the OU. Next, if the file has new contacts to import, import them! The script has two variables up in the "customizations" section that you can change for your specific OU and of course, the path to your CSV file's location. The structure of the CSV file is:

displayName,mail,givenName,sn,mailNickname,Company

The PowerShell (.ps1) script is below for anyone who could benefit from this. Make sure you run it as a user that has access to the OU you're syncing and enjoy!



#

#Exchange 2008 Contact sync with CSV file



#

#Set customizations here

$syncOU="Students"

$importFile="C:\temp\ExchangeImport.csv"



#

#Global Variables

$removeCounter=0

$addCounter=0



#

#Check existing contacts in OU against CSV file, delete if not found

write-host "Checking existing contacts for deletions..."

$existingContacts = get-recipient -resultSize unlimited -organizationalUnit $syncOU -recipientType MailContact | 

    select -expand EmailAddresses | %{$_.smtpAddress}

$existingContacts | forEach-object -process {

    if ($_ -ne $NULL) {

        $i = $_

        if (import-csv $importFile | where-object {$_.mail -eq $i}) 

            {}

        else 

            {

            write-host "Removing contact: " $i

            Remove-MailContact -Identity $i -Confirm:$false

            $removeCounter++

            }

    }

}



#

#Check CSV file for new addresses against OU, create if not found

write-host "Checking CSV file for new contacts..."

import-csv $importFile | 

	forEach-object -process {

		if (get-contact -erroraction silentlycontinue -organizationalUnit $syncOU $_.mail) 

			{} 

		else 

			{

            write-host "Adding contact from CSV file:"

            new-mailContact -Name $.displayName -FirstName $.GivenName -LastName $_.sn `

                -Alias $.mailNickname -ExternalEmailAddress $.mail `

                -PrimarySmtpAddress $_.mail -OrganizationalUnit $syncOU

            set-contact -identity $.mailNickname -WindowsEmailAddress $.mail -Company "$syncOU"

            $addCounter++

            }

    }

    

#

#Statistics Output

write-host "Attempted to delete " $removeCounter " contacts from the " $syncOU " OU."

write-host "Attempted to add " $addCounter " contacts to the " $syncOU " OU."

NOBODY puts Newsstand in a folder!

nospam@example.com (Khanh Tran) — Wed, 12 Oct 2011 19:36:56 -0700

I just updated to IOS5 on my iPhone 3GS. Everything seems to work great so far, but I guess we can't put the Newsstand app in a folder? Is this true? Anyone else have this problem?

Installing Windows XP on a Dell Inspiron 1525 (downgrading from Windows Vista)

nospam@example.com (Khanh Tran) — Thu, 07 Feb 2008 21:36:46 -0700

I recently came by a new Dell Inspiron 1525 that someone I know purchased. It originally came with Windows Vista Home Premium loaded from the factory, but the owner (like many others) preferred Windows XP Professional. With a little help from the links below, you can install all of the necessary drivers needed to get this laptop working with Windows XP!

First off, you'll need the SATA drivers on a USB floppy. There are other means of satisfying the Windows XP installer's lack of SATA drive support, but you're own your own past this link:
SATA controller: Intel Corporation 82801HBM/HEM (ICH8M/ICH8M-E) SATA AHCI Controller (rev 02)

Once XP is installed, I went straight for the wireless card driver:
Dell Wireless 1390 (Broadcom BCM 4311) Windows Update has the Creative Labs Webcam (built in to the top of the screen) and the Marvell Yukon 88E8040 PCI-E Fast Ethernet Controller drivers. If you need the wired ethernet controller driver before the wireless, you can try the Marvell site and search for the Yukon family driver. It will have the driver, plus other utilities if you need support for things like 802.1q VLANs, etc.

Finish out the drivers, chipsets, and Dell hotkey support with:
SIGMATEL STAC 92XX C-Major HD Audio Chipset Conexant D330,HDA,MDC,v.92,modem Touchpad Intel GM965 (Video Card) Dell Quickset Ricoh R5C833 (Flash Drive controller)

This particular Dell Inspiron didn't have bluetooth installed (the BIOS showed no card, even though there was an LED for it), but if your's has the Dell Wireless 355 Bluetooth Module, you'll need the XP Downgrade patch to enable Bluetooth and then the actual Windows XP Driver

compare a burned dvd or cd with iso file in linux

nospam@example.com (Khanh Tran) — Sat, 26 Mar 2011 18:06:30 -0700

This is something I've been meaning to write for a while. By using this script and md5sum, you can verify that data burned to CD/DVD matches the original ISO file in Linux. It's a bit tricky, as it's not as simple as just running md5sum against /dev/dvd (the whole disc). That's because more than just the data in the ISO is written to the media (finalizing the disc, etc.).

#!/bin/bash

#Script to check md5sum of iso file against disc in drive
#DEPENDS on md5sum existing in path
#
#script should be called like:
# ./md5check.sh file.iso /dev/dvd

ckFile=$1
ckDrv=$2

echo "Getting file extents..."
fext=$(( $(ls -l $ckFile | awk '{ print $5 }') / 2048 ))

echo "Getting md5sum of file..."
fileMD5sum=`cat $ckFile | md5sum`

echo "Getting md5sum of disc in drive..."
drvMD5sum=`dd if=$ckDrv bs=2048 count=$fext | md5sum`

echo "File md5sum: " $fileMD5sum
echo "Drive md5sum: " $drvMD5sum

if [ "$fileMD5sum" = "$drvMD5sum" ]; then
echo " "
echo "md5sum of" $ckFile "and" $ckDrv "match."
echo " "
else
echo " "
echo "********************************"
echo "******** WARNING!!! **********"
echo "********************************"
echo "** md5sum DOES NOT MATCH!!! ***"
echo "********************************"
echo "********* WARNING!!! **********"
echo "********************************"
echo " "
fi