F-SECURE INTERNET GATEKEEPER FOR LINUX 4.01 Administrator's Manual page 114

Overview of operations:
The following describes how clients connect to servers when F-Secure Internet Gatekeeper for Linux
is set up as a transparent proxy:
1 The client starts a connection to a service port (example 110) of a server (SERVER).
2 Access requests from clients pass through F-Secure Internet Gatekeeper for Linux, which is
placed as a bridge between clients and the NAT (lower-level) router.
3 FSIGK redirects the access request from the client to FSIGK:9110 based on the NAT setting in
iptables and stores the original access destination (SERVER:110).
4 FSIGK listens to the access at VIRUS:9110 and retrieves the access request replaced by iptables.
Afterwards, Internet Gatekeeper retrieves the original destination (SERVER:110), which is stored
in iptables, and sends the access request to the original destination (SERVER:110).
Settings
To use a transparent proxy in bridge mode, configure the network and server associated with
F-Secure Internet Gatekeeper for Linux in the following way:
1 Open the web console. Select Proxy settings. Start up each service in transparent proxy mode:
Proxy settings
HTTP proxy
Proxy port
Transparent proxy
SMTP proxy
Proxy port
Transparent proxy
POP proxy
Proxy port
Transparent proxy
FTP proxy
Proxy port
Transparent proxy
After configuring the settings, check that the client can access the port of each service (9080, 9025,
9110, 9021) on Internet Gatekeeper.
2 If you use Linux kernel 2.4, apply a patch to the kernel and recompile with the following settings. If
you use Linux kernel 2.6, you do not need to perform the following steps (recompiling the kernel).
F-Secure Internet Gatekeeper for Linux/Administrator's Guide
: On
: 9080
: On
: On
: 9025
: On
: On
: 9110
: On
: On
: 9021
: On
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