network monitoring tool
 

Is there any tool to monitor the network, which will the details of the client which ahve accessed a particular system, accessed files, date & time of access?
I prefer to get a software which will run on both win & linux

Hmm... I guess you need software installed on netwoked machines... Or just a tcpdump, but it's much harder. If not, web server logs+ftp server logs+samba logs+.... should do.

It sounds more like you want system monitoring tools rather than network monitoring tools. Check out apps like: syslog, Tripwire, AIDE, swatch, etc. Turn up logging and start digging...

If you really want network tools, check out apps like: tcpdump, snort, ethereal, etc.