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6.8.1 CONFIGURING NETWORK FORWARDING AND IP MASQUERADING
To use a console server as an Internet or external network gateway requires establishing an external network connection and then
setting up forwarding and masquerading.
By default, all console server models are configured so that they will not route traffic between networks. To use the console server
as an Internet or external network gateway, forwarding must be enabled so that traffic can be routed from the internal network to the
Internet or an external network.
NOTE: Network forwarding allows the network packets on one network interface (for example, LAN1/eth0) to be forwarded to another
network interface (for example LAN2/eth1 or dial-out/cellular). Locally networked devices can IP-connect through the console
server to devices on a remote network. IP masquerading is used to allow all the devices on your local private network to hide
behind and share the one public IP address when connecting to a public network. This type of translation is only used for
connections originating within the private network destined for the outside public network, and each outbound connection is
maintained by using a different source IP port number.
Navigate to System > Firewall.
FIGURE 6-19.
Select the Forwarding & Masquerading tab.
Find the Source Network to be routed and tick the relevant Destination Network.
For example, to configure a single-Ethernet device such as the LES1204A-G as a cellular router, set:
- the Source Network to Network Interface
- the Destination Network to Dialout/Cellular.
IP Masquerading is generally required if the console server will be routing to the Internet, or if the external network being routed to
does not have routing information about the internal network behind the console server.
IP Masquerading performs Source Network Address Translation (SNAT) on outgoing packets to make them appear like they’ve come
from the console server rather than devices on the internal network.
When response packets come back devices on the external network, the console server translates the packet address back to the
internal IP, so that it is routed correctly. This allows the console server to provide full outgoing connectivity for internal devices using
a single IP Address on the external network.
CHAPTER 6: FIREWALL, FAILOVER AND OOB ACCESS
