A network of 4 PC, including a file server, has recently had issues with maxing out their ISP's internet cap. Even after 'upping' to a current package almost 10x in size, they are still finding they're having problems (in fact, the phantom usage seems to have increased to accommodate the increase in cap - that's stumped me entirely!). Wi-Fi security has been checked and updated, but this has made no change.
Multiple MBAM & NOD32 scans have been run on all systems, on a few different days - nothing found. Zemana antilogger has been placed onto the (file) server, but nothing has been picked up as yet.
Still, the increased traffic appears, even when only one user is there (and he's the business owner, and has told me exactly what he is running).
Any ideas on (free) tracking software which I can install on each system which would allow me to at very least isolate which PC/s contain the software causing the problem (as I suspect it is some sort of malicious software on the given PC/s which we haven't yet detected but which is causing these problems)?