Log local network traffic into file

Question

I want to log the receive data speeds of a NIC card in linux into a text file. What is the best way to do something like this (not afraid of using terminal)

Answer 1

#!/bin/bash

if [[ -z ${1} ]]; then
    echo "You must provide an interface to monitor"
    exit
fi

nic="${1}"
while true; do
    SPEED=$(cat /proc/net/dev | grep $nic |awk '{$1=$1};1' | cut -d' ' -f 2)
    TIME=$(date +%s)
    echo "$TIME,$SPEED" >> /tmp/log-bandwidth-$nic-$(date '+%Y-%m-%d')
    sleep 5
done

If you create this as a file, say bandwidth-monitor.sh, then you can run it and provide the network interface to monitor:

bash bandwidth-monitor.sh eno1

This will create a file in /tmp (which you can modify. For example:

tail -f /tmp/log-bandwidth-eno1-2022-06-03