Published at LXer:

A controlled dial-on-demand router is a convenient tool. An uncontrolled dial-on-demand router is not. The Wireshark network protocol analyzer helped me track down the cause of some strange and unwanted dialup connections. Wireshark is a 20MB download. The GPL-licensed utility runs under Linux, Unix, Mac OS X, and Windows. The problems I needed to solve were all with a Windows client. My SMC Barricade 7004AWBR wireless router has an RS-232 port and can control an external modem, which I use for Internet connectivity. While there is quite a bit of Ethernet traffic on my network between several Windows machines and a Linux server, only a small portion of the traffic is addressed to the gateway, calling for an outside connection. Connections are made automatically if required, and if the connection is idle for a specified interval, the router quietly drops the connection and waits for later requests to dial out again.

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