F-SECURE INTERNET GATEKEEPER FOR LINUX 4.01 Administrator's Manual page 110

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 The NAT (lower-level) router relays the access request from the client to F-Secure Internet
Gatekeeper for Linux (FSIGK) that is set on the default route.
3 FSIGK redirects the access request from the client to FSIGK:9110 on the basis of 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 has been stored in iptables and sends the access request to the original destination
(SERVER:110).
Settings
To use a transparent proxy in proxy mode, configure the network and server associated with F-Secure
Internet Gatekeeper for Linux in the following way:
1 Open the web console. Select
mode:
Proxy Settings
Proxy settings
HTTP proxy: On
Port Number: 9080
Transparent proxy: On
SMTP proxy: On
Proxy port: 9025
Transparent proxy: On
POP proxy: On
Proxy port: 9110
Transparent proxy: On
FTP proxy: On
Proxy port: 9021
Transparent proxy: On
After configuring the settings, check that the client can access the port of each service (9080, 9025,
9110, 9021) on Internet Gatekeeper.
F-Secure Internet Gatekeeper for Linux/Administrator's Guide
and then start up each service in transparent proxy
Proxy settings
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