I'm running a corporative OpenVPN server in an Ubuntu Server 14.04.3 Intel Xeon E3 machine.
I need to log each connection try to any website, including destination IP, hostname, date, up/down bandwidth used and the VPN user who performed the connection.
I DO NOT need to log the actual data, just the connection details.
I've tried to develop a bash script using tcpdump, but it becomes complicate to link outgoing connections from the server (made from eth0) with the client in tun0 interface. Also, I'm not sure about the performace of tcpdump in such a production server, it seems to be a debug tool.
So, any idea on this topic?