The Rdr Rule: Allowing External Access; To A Lan Computer - SMC Networks Barricade SMC7401BRA User Manual

The RDR rule: Allowing external access to a LAN
computer
You can create an RDR rule to make a computer on your LAN,
such as a Web or FTP server, available to Internet users without
requiring you to obtain a public IP address for that computer.
The computer's private IP address is translated to your public
IP address in all incoming and outgoing data packets.
Note:
The following example illustrates using the RDR rule to provide
external access to your web server:
Your ADSL Barricade receives a packet containing a request
for access to your Web server. The packet header contains the
public address for your LAN as the destination IP address, and
a destination port number 80. Because you have set up an RDR
rule for incoming packets with destination port 80, the device
recognizes the data as a request for Web server access. The
device changes the packet's destination address to the private IP
address of your Web server and forwards the data packet to it.
Your Web server sends data packets in response. Before the
ADSL Barricade forwards them on to the Internet, it changes
the source IP address in the data packets from the Web
server's private address to your LAN's public address.
Without an RDR rule (or Bimap rule described on
page 81) the ADSL Barricade blocks attempts by
external computers to access your LAN computers.
Adding NAT Rules
73