From TT Analytics:
RexTrafficMonitor is a small and easy-to-use utility (Sniffer) that monitors the traffic on your LAN. RexTrafficMonitor displays information about received packages such as direction (sender's and receiver's IP address and port) and size and writes this information into LOG-file. RexTrafficMonitor allows filtering received packages by IP address or by port number. Also RexTrafficMonitor has trigger mechanism to start another program when some criteria is met for example SMB or SMTP connection. RexTrafficMonitor displays the information about packages sent not only from/to a computer on which it has been installed.