A typical configuration example of transparent proxy mode is shown as follows:
Transparent Proxy Example
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In this example, the remote client’s address is 172.16.0.99 , and it is attempting to connect to
the server at 10.0.0.99 , port 80 . The front-facing firewall is configured to route
traffic for 10.0.0.99 through the Enterprise Gateway at address 192.168.0.9 . The server is
configured to use the Enterprise Gateway at address 10.0.0.1 as its default IP router.
The Enterprise Gateway is multi-homed, and sits on both the 192.168.0.0/24 and 10.0.0.0/24
networks. It is configured with a listening interface at address 10.0.0.99:80 ,
with transparent proxy mode switched on, as shown in the following Configure HTTP Interface
dialog:
The Enterprise Gateway accepts the incoming call from the client, and processes it locally. However, there is no
communication with the server yet. The Enterprise Gateway can process the call to completion and respond to the
client—it is masquerading as the server.
If the Enterprise Gateway invokes a connection filter when processing this call (with transparent proxying enabled),
the connection filter consults the originating address of the client, and binds the local address of the new
outbound connection to that address before connecting. The server then sees the incoming call on the Enterprise Gateway
originating from the client (172.16.0.99 ), rather than either of the Enterprise Gateway's IP addresses.
The following dialog shows the example configuration for the Connect to URL filter:
The result is a transparent proxy, where the client sees itself as connecting directly to the server,
and the server sees an incoming call directly from the client. The Enterprise Gateway processes two separate
TCP connections, one to the client, one to the server, with both masquerading as the other on each
connection.
Note: Either side of the transparent proxy is optional. By configuring the appropriate
settings for the incoming interface or the connection filter, you can masquerade only to the server, or only
to the client.
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