F-Secure Internet Gatekeeper for Linux/Administrator’s Guide
137
Transparent Proxy mode (Router or Bridge)
Client
Internet Gatekeeper (fsigk, 0.0.0.1)
SMTP server (smtpserver, 0.0.0.2)
TCP connect(to:
0.0.0.2:25)
----------------------------->
TCP connect(to:
0.0.0.2:25)
----------------------------->
220 smtpserver ...
220 fsigk ...
<-----------------------------
<-----------------------------
EHLO client
----------------------------->
EHLO fsigk
----------------------------->
250-smtpserver ...
250-smtpserver ...
<-----------------------------
<-----------------------------
MAIL FROM:
<fromuser@fromdomain>
----------------------------->
MAIL FROM:
<fromuser@fromdomain>
----------------------------->
(the rest is processed in the same way as in proxy mode)