Transparent Mode Internet Access - D-Link NetDefendOS User Manual

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Figure 4.23. Non-transparent Mode Internet Access

The non-switch route usually needed to allow Internet access would be:

Now suppose the NetDefend Firewall is to operate in transparent mode between the users and

the ISP. The illustration below shows how, using switch routes, the NetDefend Firewall is set up

to be transparent between the internal physical Ethernet network (pn2) and the Ethernet

network to the ISP's gateway (pn1). The two Ethernet networks are treated as a single logical IP

network in Transparent Mode with a common address range (in this example 192.168.10.0/24).

Figure 4.24. Transparent Mode Internet Access

In this situation, any "normal" non-switch all-nets routes in the routing table should be removed

and replaced with an all-nets switch route (not doing this is a common mistake during setup).

This switch route will allow traffic from the local users on Ethernet network pn2 to find the ISP

These same users should also configure the Internet gateway on their local computers to be the

ISPs gateway address. In non-transparent mode the user's gateway IP would be the NetDefend

Firewall's IP address but in transparent mode the ISP's gateway is on the same logical IP network

as the users and will therefore be gw-ip.

NetDefendOS May Also Need Internet Access

The NetDefend Firewall also needs to find the public Internet if it is to perform NetDefendOS

functions such as DNS lookup, Web Content Filtering or Anti-Virus and IDP updating. To allow

this, individual "normal" non-switch routes need to be set up in the routing table for each IP

address specifying the interface which leads to the ISP and the ISPs gateway IP address.

If the IPv4 addresses that need to be reached by NetDefendOS are 85.12.184.39 and

194.142.215.15 then the complete routing table for the above example would be:

The appropriate IP rules will also need to be added to the IP rule set to allow Internet access

85.12.184.39

194.142.215.15

Chapter 4: Routing

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