Lightning SA MultiCom, User Manual

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Chapter 3 Getting Started
50 MultiCom Firewall User’s Manual
Option 5: Advanced Configuration for advanced users. This gives you access
to all of the parameters of your MultiCom Firewall. Setting these options
requires a good understanding of network terminology and the way your own
network is configured. Please refer to the Lightning-Linux Reference Manual for
a description of Advanced Configuration options.
Special Configurations
If your modem cannot be configured into “bridge” mode you will have to let the
Broadband Modem receive the actual IP parameters from the ISP and share it
with the MultiCom Firewall. In this case you have to make a special
configuration to use the MultiCom Firewall.
Only choose one of these configurations if you cannot use the Common
Configurations above.
1. Broadband Modem receives IP from ISP and is a DHCP server.
2. Broadband Modem receives IP from ISP and has a fixed IP on its LAN
interface.
3. Network router is between Modem and Firewall.
4. Network router is between Firewall and Local Network.
CAUTION - Because you will be creating 2 networks, one between the
MultiCom Firewall and the Broadband Modem and one between the
MultiCom Firewall and the local network you must be sure that both
are using different subnets. For example the default LAN interface
uses subnet 10.0.0.0/255.0.0.0 so if this was used in the final
configuration the WAN should have a different subnet.
When connecting the MultiCom Firewall to a network that is not directly on the
Internet the Firewall will rely on the functionality of the devices between it and
the Internet or between it and the Local Network. Some services might be limited
or require additional configuration as described below.
• the Network Address Translation (NAT) of the Broadband Modem may not
be as powerful as the MultiCom Firewall’s NAT
• if the Broadband modem is using NAT then redirection of incoming traffic to
reach internal servers requires NAT rules on BOTH the Broadband Modem
and the MultiCom Firewall (including configuration for remote access of the