Now with LTE I have a data traffic limit of 30GB per month. First I thought that this is plenty of traffic because with my old DSL I used around 20GB only. But guess what, when having faster download speed all systems seem to generate more traffic than before.
One day I noticed 600MB traffic over night and I didn’t know what was causing it*.
Since the Telekom Router does not provide any usefull information about the traffic I decided to use a Raspberry Pi to monitor the network traffic.
800mA USB Power supply
USB 100Mbit Network Adapter
Linux + Bridge Control + tcpdump
I configured the Raspberry Pi as a Ethernet Bridge device (using brctl) and attached it between my Ethernet Switch and the Telekom Router. The WLAN traffic of the Telekom Router will not flow through the bridge, but I don’t use the Telekom Router for WLAN anyway.
*btw. the 600MB traffic where caused by a Linux system doing background updates (packagekit)