fakemac - make your switch "dumb" hub

Author: Hajime Fujita [email protected]

Introduction

This tool hides the real MAC address of your NIC to prevent switch from learning your address. When a switch does not have an entry in its MAC address table, it broadcast a frame to the whole collision domain (i.e. "flooding" mode). This is sometimes useful when you are constructing single IP address cluster based on broadcast-based mechanism.

This tools is implemented as a Linux kernel module and supports up to kernel 2.6.35.

Build

To build the module, type

# cd kmod
# make

If you want to build a module for a kernel other than currently running on your machine, use KERNELDIR variable to specify the location of your target kernel.

# make KERNELDIR=/path/to/your/kernel

Usage

To use fakemac, first load the module.

# insmod fakemac.ko

After the successful loading of the module, you'll see several files under the /proc/sys/net/fakemac directory.

If you want to hide the real MAC address of eth0, type the following command:

# echo 1 > /proc/sys/net/fakemac/eth0

As you may imagine, you can disable fakemac by doing this:

# echo 0 > /proc/sys/net/fakemac/eth0

By default, fakemac is disabled for all network interfaces.

Acknowledgment

The idea of this tool comes from Microsoft Windows Server Network Load Balancing (NLB) multicast feature.

This tool has been developed under the JST CREST "Dependable Operating System for Embedded Systems Aiming at Practical Applications" project.