July 15th, 2008

Webserver Based On ATMega88

Webserver Based On ATMega88

Before starting this Ethernet project the author did of course some prototyping and then he noticed alreadythat UDP was not a problem with lots of space left on the atmega88. Therefore he was quite confident that TCP + HTTP will work. TCP/IP was invented more than 25 years ago. Todays microcontrollers provide almost the computing power a standard computer had at that time. No java or xml was used at that time. Things were done in smart and efficient ways.

As you can imagine this web-server code is written for a friendly environment. Don’t put it on the open internet. The code uses e.g the incoming packet to build from it the outgoing packet. An attacker who sends a mal formed IP packet might be able to confuse the TCP/IP stack. The code is verified with a lot of different browsers and a number of operating systems. It was tested Linux, BSD Unix, Win 98, Win XP, Mac OS-X with a number of different web browsers. It works very well but it was not tested agains atacks and destroy tests.

Webserver Based On ATMega88: [Link][via]

Install SNMP (Simple Network Management Protocol) on Debian     This is an update to a previous post regarding the change of mac address in Debian. In the previous tutorial I told you can change it by ifconfig from a root account. Now I’m going to teach you how to set an interface mac address using /etc/network/interfaces . This is a better way to set your mac address because the mac you set in /etc/network/interfaces will always load when the interfaces are loaded so you don’t have to worry about the mac after reboot for example. Let’s start by looking at my /etc/network/interfaces it looks like this:

#This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet static
dns-search .com
hwaddress ether 00:01:04:1b:2C:1F

Open this file in your favorite editor. I use nano. You can see that my ip address is and my gateway is instead of these in your file you will see your network settings. Now, under the last line of the interfaces file you have to add the following

hwaddress ether 00:01:04:1b:2C:1F

replacing 00:01:04:1b:2C:1F with the mac you want to assign to the interface where you are adding the line. Now save the file with ctrl+x then y to confirm and restart the network service with
/etc/init.d/networking restart
Now type ifconfig and there it is you should see the mac you entered earlier assigned to eth0 (if you choused eth0). You’re done the mac will now load every time the network load’s.

    Although the physical MAC address is permanent by design and is assigned to your network card by factory several mechanisms allow the modification, or spoofing of the MAC address that is reported by the operating system. This can be useful if you want to keep your privacy or to ensure interoperability. Some internet service providers bind their service to a specific MAC address; if you change your network card or intend to install a router the service won’t work anymore. Changing the MAC address of the new interface will solve the problem.

    Under Linux the MAC address of a network card can be changed by doing the following under a root account.

/etc/init.d/networking stop

ifconfig eth0 hw ether 02:01:02:03:04:08

/etc/init.d/networking start

” 02:01:02:03:04:08” being the new assigned mac.

    Under Fedora Core 5, and possibly in other Linux distributions, to disable and restart networking, you must stop and start /etc/init.d/network, instead of /etc/init.d/networking. Using the described method your MAC address will revert to original MAC address (hardware MAC) after reboot. So if you want to make the change permanently in Debian you have to add

hwaddress ether 02:01:02:03:04:08

into the appropriate section of /etc/network/interfaces so that the MAC address is set when the network device is started.

You can also use the tool MACChanger to change the MAC address under Linux.

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