Aleksandar's computer workshop

Let's see what Aleksandar was fixing today.
My findings, tips & tricks related to computers, internet, programming and other stuff I was working with.

Best way to practice and learn how to manage complex networks

Just use GNS3!

GNS3 is a graphical network simulator that allows simulation of complex networks.
To allow complete simulations, GNS3 is strongly linked with :

  • Dynamips, the core program that allows Cisco IOS emulation.
  • Dynagen, a text-based front-end for Dynamips.
  • Qemu, a generic and open source machine emulator and virtualizer.

GNS3 is an excellent complementary tool to real labs for network engineers, administrators and people wanting to pass certifications such as CCNA, CCNP, CCIP, CCIE, JNCIA, JNCIS, JNCIE.

It can also be used to experiment features of Cisco IOS, Juniper JunOS or to check configurations that need to be deployed later on real routers.

This project is an open source, free program that may be used on multiple operating systems, including Windows, Linux, and MacOS X.

Features overview

  • Design of high quality and complex network topologies.
  • Emulation of many Cisco IOS router platforms, IPS, PIX and ASA firewalls, JunOS.
  • Simulation of simple Ethernet, ATM and Frame Relay switches.
  • Connection of the simulated network to the real world!
  • Packet capture using Wireshark.

Some usefull links:

A lot of documentation and video tutorials

Download page


Fixing power connector on ASUS M6000 (M6N) laptop

Today I got ASUS M6N laptop for repair. It did not want to turn on and also it does not give any sign that it’s charging the battery.

Laptop was previously sent by it's owner to ASUS repair center and paid 70 EUR only for diagnostics. ASUS came up with 600 EUR bill for repair so owner did not accepted the offer. They suggested motherboard and HDD replacement (?!). I did not understand why HDD because HDD works just great.

Anyway, laptop finished at my place and after 1.5h work laptop is working again! It needed some dust cleaning and bit soldering...

First I had to find disassembly or service manual. Bit of Googling and visiting some favorite sites I found the manual here

After laptop is taken apart I made these pictures (click on image for high resolution):

CPU and surrounding covered with dust.

Loose broken power plug and very dirty fan

Again broken plug after I have "shaked" the laptop a bit. Now you can also see the rest of the power connector.

Bigger picture of the open case and power connector location

Here is the "guilty" part

Which came out from here... Good luck that motherbord and othr parts are not affected with accident

After operation it looks like this. Metal part is soldered properly to the motherboard.
I have melted together top part of the connector case to assure better joint.

As you can see everything is clean and neat again.

How to enable AHCI mode after installing Windows

AHCI (Advanced Host Controller Interface) is present on newer Intel chipsets such as 975X (ICH7), P965 (ICH8), and P35 (ICH9). AHCI mode is enabled in the BIOS and 3 settings are commonly available: IDE, AHCI, and RAID. The last two (AHCI and RAID) require a driver floppy and the F6 method when installing Windows XP otherwise the hard disks won't be detected.

AHCI mode brings 3 main advantages:
Supports NCQ (Native Command Queuing) allowing SATA drives to accept more than one command at a time and dynamically reorder the commands for maximum efficiency.
Supports hot plugging of devices
Supports staggered spin ups of multiple hard drives at boot time

However, in the real world the performance difference isn't huge.

The problem is that if you installed Windows in IDE mode (i.e. you didn't use F6 and supply a driver disk), then simply changing the BIOS setting to AHCI mode and rebooting will cause Windows to fail and will require a repair install. Most people have been advising to reinstall Windows if you want AHCI enabled.

Here you will find the sollution :

Copy of the article is here (5.07 kb)

How to determine that hardware DEP is available and configured on your computer

To confirm that hardware DEP is working in Windows, use one of the following methods.

You can use the Wmic command-line tool to examine the DEP settings. To determine whether hardware-enforced DEP is available, follow these steps:


Click Start, click Run, type cmd in the Open box, and then click OK.


At the command prompt, type the following command, and then press ENTER:

wmic OS Get DataExecutionPrevention_Available

If the output is "TRUE," hardware-enforced DEP is available.

To determine the current DEP support policy, follow these steps.


Click Start, click Run, type cmd in the Open box, and then click OK.


At the command prompt, type the following command, and then press ENTER:

wmic OS Get DataExecutionPrevention_SupportPolicy

The value returned will be 0, 1, 2 or 3. This value corresponds to one of the DEP support policies that are described in the following table.

DataExecutionPrevention_SupportPolicy property value

Policy Level



OptIn (default configuration)

Only Windows system components and services have DEP applied



DEP is enabled for all processes. Administrators can manually create a list of specific applications which do not have DEP applied



DEP is enabled for all processes



DEP is not enabled for any processes

Note To verify that Windows is running with hardware DEP enabled, examine the DataExecutionPrevention_Drivers property of the Win32_OperatingSystem class. In some system configurations, hardware DEP may be disabled by using the /nopae or /execute switches in the Boot.ini file. To examine this property, type the following command at a command prompt:

wmic OS Get DataExecutionPrevention_Drivers

Output sample on my PC: