Kerio Tech Firewall6 manual 226

Chapter 16 Other settings

Second, there must be no default gateway in the operating system (no default gateway must be defined for any network adapter). This condition does not apply to the dial-up line which is used for the Internet connection — this line will be configured in accordance with information provided by the ISP.

If WinRoute receives a packet from the local network, it will compare it with the system routing table. If the packets goes out to the Internet, no record will be found, since there is no default route in the routing table. Under usual circumstances, the packet would be dropped and a control message informing about unavailability of the target would be sent to the sender. If no default route is available, WinRoute holds the packet in the cache and dials the appropriate line if the demand dial function is enabled. This creates an outgoing route in the routing table via which the packet will be sent.

To avoid undesired dialing of the line, line dialing is allowed by certain packet types only. The line can be dialed only by UDP or TCP packets with the SYN flag (connection attempts). Demand dialing is disabled for Microsoft Networks services (sharing of files and printers, etc.).

Since this moment, the default route exists and other packets directed to the Internet will be routed via a corresponding line. The line may be either disconnected manually or automatically if idle for a certain time period. When the line is hung-up, the default route is removed from the routing table. Any other packet directed to the Internet redials the line.

Notes:

1.To ensure correct functionality of demand dialing there must be no default gateway set at network adapters. If there is a default gateway at any interface, packets to the Internet would be routed via this interface (no matter where it is actually connected to) and WinRoute would not dial the line.

2.If multiple demand dial RAS lines are defined in WinRoute, the one that was defined first will be used. WinRoute does not enable automatic selection of a line to be dialed.

3.Lines can be also dialed if this is defined by a static route in the routing table (refer to chapter 16.1). If a static route via the dial-up is defined, the packet matching this route will dial the line. This line will not be used as the default route — the Use default gateway on remote network option in the dial-up definition will be ignored.

4.According to the factors that affect total time since receiving the request until the line is dialed (i.e. line speed, time needed to dial the line, etc.) the client might consider the destination server unavailable (if the timeout expires) before a success- ful connection attempt. However, WinRoute always finishes dial attempts. In such cases, simply repeat the request, i.e. with the Refresh button in your browser.

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