The Port Mapping Window allows you to view and modify the Network Address Translation (NAT) table used for IP masquerading. The table at the top of the window displays the current translation entries and can be updated by pressing the "Refresh" or "Monitor" button. Uncheck "Show Static Only" and press Monitor to see the entire NAT table.
To Add or Remove a NAT table entry, select a row from the table if desired. This will copy the corresponding information to the edit fields in the "Configure Entry" area. Use the edit fields and controls in this area to change the information as desired, and then press "Add" or "Remove" to update the table.
NAT table entries are created dynamically when a host on your private LAN accesses the public Internet. To allow hosts on the public Internet to initiate a connection to a host on your private LAN, you can create a "static" translation entry. Dynamic entries are aged periodically and automatically deleted when they are no longer needed. Static entries remain in the table until you remove them or quit the application. Static entries can be saved and later restored by opening the corresponding configuration document.
The "Age" column in the table indicates the number of 30 second intervals since this entry was last used. If a dynamic entry has not been used in over 60 intervals (30 minutes) it is automatically deleted. When a TCP connection is Reset or closed from both ends, the entry is set to be deleted in one minute.
The "Flags" column indicates the type and status of each entry as follows:
S static entry
FL Local host has closed connection (TCP FIN packet)
FR Remote host has closed connection (TCP FIN packet)
Special Cases (experimental):
Since static entries are not aged, you can use the "Age" value to specify the length of a port range. A static entry that maps apparent port 6000 to actual port 6000 with an age of 1000 will map any port number between 6000-7000 to the corresponding actual address.
If you specify an actual endpoint of 0.0.0.1:0, the apparent IP address will be used as a secondary NAT address allowing datagrams received on this address to be translated for use with Telco Return cable modems.
Detailed instructions for using IPNetRouter are available on the Sustainable Softworks web site at <http://www.sustworks.com>.
