vincentkong.com

I’m an owners of two IBM Thinkpad; the T40, and the T42, both running on Windows XP. A few days ago both of were experiencing problems with the laptops.

With the T42 Thinkpad, I would lose my wireless connection a few moments after I have turned on the laptop. When I try to ping my router I would get a “Hardware Error” message, and when viewing the Network Connections under Control Panel, the Wireless Connection indicated that it was disabled. An attempt to re-enable the connection would result in the laptop hanging.

The T40 Thinkpad was even worse, as it was haunted by the Blue Screen of Death.The blue screen would appear randomly and very frequently, making it almost impossible to diagnose what was the cause.

It turned out the root case was the drivers for the Intel PRO/Wireless 2200BG wireless card, which is the card that was installed on both our laptops.Apparently, the existing drivers which came with the IBM Thinkpad was no longer compatible with newer Access Points (I had also recently change my wireless network encryption from WEP to WPA).I downloaded the latest drivers from, and after installing it, both laptops were working again.

For more information refer to the Intel WiFi Product support page.

Last week I flashed my Linksys WRT54GL router with a 3rd party firmware DD-WRT v23 SP. The installation resolved my issues with the original Linksys firmware of not being able to surf the internet while downloading with bittorrent. However, I found connectivity was still a bit sluggish and at times it was difficult to access the DD-WRT web administration interface.

I found some performance tips related to router slowdown from the DD-WRT Wiki website, and implemented one of the solutions recommended on the page:

• Go to the Web-Admin and log in
• Go to ‘Administration’
• Go to ‘Management’
• Enter the following values at ‘IP Filter Settings’
  • Maximum Ports: 4096
  • TCP Timeout (s): 3600 to 90 (decrease if you have many TCP connections)
  • UDP Timeout (s): 3600 to 90 (decrease if you have many UDP connections)

This weekend, I was assigned to do load testing from my home for a project at work. The load testing involved running with 10 to 20 users, with each user running 2000 iterations. With the number of open connections the load testing will make, I was pretty sure the original Linksys firmware would not be able to handle it, so I was curious on how the DD-WRT firmware would perform.

The results was very promising, after running the load testing for an hour, my network was still running smoothly, and I had no connectivity issues with surfing the internet. I was also, able to download bittorrent and watch streaming video at the same time without experience any latency. I checked the status page of the router and found that the router was experiencing very high load for over a long period of time, as well it had 94% active connections of the available 4096.

Occasionally, I have been having trouble surfing the internet when I’m using bittorrent at the same. In the past, all I had to do was reset the router by unplugging the power. Later, I followed some tips of optimizing my connections and restricted my global connection to under 200. This helped a lot and I haven’t need to reset my router anymore for a while.

For the past 2 weeks the connectivity issue has come back again and reseting the router no longer helps anymore. The only way I can resolve the issue is to power down the boardband modem until I get a new IP address assign to me when it restarts.

I decided to take some risk and install a 3rd party firmware for my router as they are often tuned for higher loads. The two most popular firmwares I found are:

• DD-WRT
• OpenWrt

Both are GNU/Linux based firmware for embedded devices. I decided to try out DD-WRT because it had a better web interface, as well, as of version v23 was completely rewritten and the Linux Kernel is based on the OpenWrt Kernel.

I flashed my router with the standard generic version of v23 SP2 which can be downloaded from their website. The actually flashing was relatively easy, I just did a firmware upgrade using web administration interface from the original Linksys firmware.

One issue I had, was that I wasn’t able to access the web administration interface for DD-WRT after the flashing. However, that was resolved when I hard reseted my router, unfortuntately all my preivous settings was gone after this, but it wasn’t too painful to set everything back up again.

This is a high level overview of what I did to build my server at home.

Hardware for the Server

For my server I recycled an older desktop, which works well since most unix operating systems uses less resources than Microsoft Windows.

Hardware Specifications for My Server:

Building the Server

I decided to build a LAMP (Linux, Apache, MySQL, PHP) platform for my server. For the Linux operating system, I chose Ubuntu because it was very easy to install, provided a lot of documentation online, as well as it had great community support.

Setting up the Network/Router

For the server I manually gave it a static local IP address 192.168.1.100. In my router I enabled port forwarding for ports 80 (for HTTP) and ports 22 (for SSH) to forward to 192.168.1.100.

Registering a Domain Name

To register for a domain name I use GoDaddy because they are currently the cheapest provider that I can find, and domain managing was through their web based interface which makes things really easy.

Setting up Dynamic DNS

My ISP provider provides me with a dynamic IP address, therefore I had to search for a DNS service that provided dynamic DNS support. I registered at ZoneEdit because it provides the service free for up to 5 domains. After successfully registering, ZoneEdit provided me with two name servers which I had to update my domain name to use through GoDaddy.

Setting up Dynamic DNS client

I use ddclient to update my dynamic DNS entries for ZoneEdit. The client is ran as a service which get executed every 5 minutes. When it awakes, it connects to my router and extracts the WAN IP address. If the address has changed then it’ll update my entry in ZoneEdit.

After I finish configuring everything I’m able to connect to my server using the domain name I registered at GoDaddy vincentkong.com. I can now then setup the rest of the services that I want to be available on my server. e.g. Apache, FTP, SSH, SMTP, etc.