1. Openwrt Introduction

OpenWrt is a highly extensible GNU/Linux distribution for embedded devices. As a third party firmware, openwrt can extend your wireless router into a powerful Linux system. With openwrt, even if your router hardware does not support “port mirroring” function, you can also enable traffic mirroring by software mirroring.

This blog will guide you to install “port-mirroring” program in your openwrt router and deploy WFilter for internet monitoring and filtering. We assume you already has an openwrt router, if not, please check openwrt homepage to get the latest firmware.

2. Port-mirroring program

Port-mirroring is an open source project sponsored by IMFirewall Software, it is designed to mirror network traffic on linux systems.

2.1. Installation

For detailed installation guide, please check Port-mirroring open source packet mirroring. In this guide, let’s take linksys wrt54g router as an example (with openwrt backfire firmware). Steps:

a). Update openwrt package list.

b). Install the port-mirroring program

opkg install http://port-mirroring.googlecode.com/files/port-mirroring_1.2-1_backfire_brcm47xx.ipk.

2.2. Configuration

You need to edit /etc/config/port-mirroring to set the mirroring target and mirrored source interfaces.

In this example, we choose “wlan0″ wireless adapter as the mirrored source interface.

2.3. Start Port-mirroring

/etc/init.d/port-mirroring start

3. Check monitoring in WFilter

Now WFilter shall be able to monitor client computers.