Cyclades-PR2000
STEP TWO
The parameters in the Timeout Menu are explained in more detail below. The preset values should be appropriate for most applications.
Timeout and Options Menu CONFIG =>SECURITY =>NAT =>TIMEOUT AND OPTIONS
Parameter | Description |
UDP Timeout | Inactivity time required before a UDP translation is removed from the translation table. |
| An entry is created in the translation table the first time a UDP packet passes through the |
| interface. Five minutes is a reasonable time. |
DNS Timeout | Inactivity time required before a DNS translation is removed from the translation table. |
TCP Timeout | Inactivity time required before a TCP translation is removed from the translation table. |
| This time should be relatively long, because under normal conditions TCP connections |
| are formally disconnected with FIN (No more data from sender) or RST (Reset |
| Connection) flags. |
TCP Flags Timeout | Inactivity time required, after the receipt of a FIN, RST, or SYN (Synchronize sequence |
| numbers) flag, before a TCP translation is removed from the translation table. This time |
| can be relatively short, because after the TCP connection has been closed, there is no |
| further need for its address translation. |
STEP THREE
The next step is to define the global address range to which the local addresses will be translated. This is done in the menu CONFIG =>SECURITY =>NAT =>GLOBAL ADDRESSES =>ADD RANGE. The First IP Address in the example in Figure 11.1 is 200.240.230.225, while the Last IP Address is 200.240.230.238.
The local address ranges must also be entered into the router in the menu CONFIG =>SECURITY =>NAT =>LOCAL ADDRESSES =>ADD RANGE. Here, the Network IP Address (192.168.0.0 in the example) and Network Mask (255.255.255.0 in the example) are entered. Since this range is to be translated, the parameter Should This Range be Translated should be set to Yes. In the example, the network 200.200.200.0 is not to be translated. This can be configured by adding a new range and setting the translation parameter to No, or by simply not adding the range.
Chapter 11 - NAT | 94 |
