iftop

libreCMC has an iftop package. It is a program which allows you to watch your connections and their bandwidth usage in real time. It does not run in the Web interface, but rather you ssh into the router and run it on the console.

It lists the the source and destination of each connection, as well as the bandwidth rate each direction. It also can display bar graphs to give you a visual on the relative bandwidth usage. And it has a few options for sorting and displaying the connections which can be useful.

It is not useful for long term logging, only for getting a live snapshot view. But it is lightweight, with the package file at about 20KB. So I plan on adding it to all my future builds.

Running it on a libreCMC router, you’ll usually need to carefully pick which interface you want to watch, using the -i option, so you find the connection information you are looking for. E.g., if you want to see the local IPs, you’ll want your LAN interface (maybe called the eth1 interface).