In a previous post, I wrote about how I setup a transparent bridge computer, which is able to monitor all network traffic passed through it. It works great, but to make it really useful, it needs some software that can report on the monitored network traffic in a useful manner. I decided to use ntop for this purpose, as it provides powerful reporting on bandwidth usage, which is exactly what I’m after. I’m not a regular Linux user, so I usually take the easy approach and install software through whatever GUI-based software manager is included. When I did this in Linux Mint however, I found the version available was not the latest, which is 5.0.1. I also learned that ntop has since been replaced by ntopng, which wasn’t available through the GUI. I’ve had some college courses in Linux/Unix administration, so I figured I could handle installing it “the hard way”. In this post, I’ll cover how I got ntop 5.0.1 running on my bridge computer.
I recently became interested in getting a better handle on bandwidth usage on our Internet connection at work. I wanted to see what I can do for free (or at least very cheap) so I started researching solutions using Linux. Before I can try out any software though, I need a computer that can do the monitoring. I decided to build a transparent bridge or “Machine-In-The-Middle”, which is a computer with two network interface cards (NICs) which are bridged together so that any traffic going to one card is passed through to the other. The bridge computer is installed in between two other nodes on the network, and any traffic passed through the bridged NICs can be monitored by the bridge computer. The bridge creates a slight delay, but is otherwise transparent to the nodes it is connected to.
Most of the information I used to guide me in setting this up came from Bridging Ethernet Connections at the Ubuntu community wiki and this page on how to setup a bridge in Debian from microHOWTO. I thought it might be pretty difficult, especially since I’m not a hardcore Linux guy, but I found it to be surprisingly easy. For the rest of this post, I’ll cover what I did to setup my transparent bridge computer.