I am using my ubuntu system as an internet gateway.
I am searching for a Network monitoring tool (Web based or command line based) with which I can see which computers from my network are communicating which domains and IP address on the internet
Also, if I can find out the top domains or IP to/from which data is sent or received from.
The thing is some system from my network is throwing bruteforce attacks and spamming outwards. I want to know exactly which system is sending out data and is causing problems to me.
All help, advices would be appreciated ! Thanks