User guide

94 Chapter 4. Configuring Special Features

The following two commands are used to globally enable/disable a local IP address (on your LAN) as the

server for that particular protocol.

[<last port>[<first private port>]]

port>[<first private port>]]

where

first port: this is the first or only port as seen by the remote end.

last port: if specified, it is used with <first port> to specify a range of ports as seen by the remote end for

the server on your LAN.

first private port: if specified, this is a port remapping of the incoming request from the remote end.

first port maps to first private port.

first port + 1 maps to first private port + 1

last port maps to first private port + last port - first port

first port through last port are the ports as seen by the remote end.

first private port through first private port + last port - first port are the equivalent ports the server on

your local LAN will receive the request.

Remember to type save to make the changes persistent across boots.

Examples:

system addserver 192.168.1.5 tcp smtp

system addserver 192.168.1.6 tcp 0

system addserver 192.168.1.6 udp 0

The router sends a server request for SMTP to 192.168.1.5 when such a request comes from any remote

router running NAT. The router sends any other server request (tcp or udp) to 192.168.1.6.

¥ Server Request Hierarchy

When handling a request from a remote router (to which the local router has NAT enabled), the local

router selects a server based on the following priority algorithm:

1. remote addserver Ñ The local router selects a server for the remote router that handles that

particular protocol/port.

2. system addserver Ñ The local router selects a global server that handles that particular protocol/

port.

3. remote addserver with port 0 Ñ The local router selects a server for the remote router that handles

that particular protocol (such as tcp/udp) and any port.

4. system addserver with port 0 Ñ The local router selects a global server that handles that particular

protocol and any port.

5. If an IP address is used for true NAT host remapping as well as for IP address/port translation, the IP

address of the local remapped host as the server is selected.