I have a working MS Windows hardware system. Networking connection is as below:
PC (onboard Realtek RTL-8139/8139C/8139C+) --> Ethernet cable --> one of the 4 LAN ports of the D-link DIR665 router --> Ethernet cable from WLAN port of D-link 665 to the WLAN port of the cable modem which connects to the ISP).

I have never been serious about Linux in the past and knows very little about Linux. I have wanted to give Linux/Knoppix 5.3.1 a try 6 months back but never has happen until two (2) weeks back.

I took out the DVD purchased 6 months ago, immediately I booted the working hardware system with it. The very first thing I did was starting up iceweasel web browser hoping to enjoy internet surfing. To my disappointment, system failed to access outside world. To this regard, I had performed the followings:
1. Checking the LAN port at PC end found the little green and amber light of the LAN port were not ON at all. This revealed the port has not been enabled, activated or is mal-function. Reboot the hardware system with Windows proved the PC LAN port is functioning (eliminating problem caused by faulty hardware).
2. I have performed various commands (suggestions from Knoppix Forum on similar problem) like Dmesg, Lsmod, lspci, ifconfig –a…., all these commands suggested eth0 is existed and driver 8139t00 is also present. The only trouble is that Netcardconfig on eth0 failed to receive DHCP response every time it is run.
3. Disconcerning the network problem, I was able to installed Knoppix 5.3.1 onto HDD with “knoppix-installer” command successfully. Of course, I was eager to try out the HDD environment but only found the same problem.

I have been googling the last one week hoping to find solution(s) on above but failed. In my humble opinion, Knoppix 5.3.1 (which I have) at system BOOTING is:
1. able to detect Realtek RTL-8139/8139C/8139C+ (display at boot time)
2. but not able to “INITIALIZE” (or “ACTIVATE”) the LAN port
- Since the hardware is not properly INITIALIZED, therefore, NETCARDCONFIG or like commands will have no
effect on the hardware (LAN port).

Lastly, to ensure DVD contents are intact , I have boot the DVD with "knoppix testdvd" cheat code but found checksum on all software are matched with release base.f

I hope someone is knowledgeable to guide me out of this fraustration.

Thanks and Regards,
Julian