F-Secure Internet Gatekeeper for Linux/Administrator’s Guide
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11.3
SMTP Proxy Process
This section describes how common protocols are processed with the SMTP proxy.
Proxy mode
Client
Internet Gatekeeper (fsigk, 0.0.0.1)
SMTP server (smtpserver, 0.0.0.2)
TCP connect(to:
0.0.0.1:9025)
----------------------------->
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>
----------------------------->
250 ok
250 ok
<-----------------------------
<-----------------------------
RCPT TO: <touser@todomain>
----------------------------->
RCPT TO:
<touser@todomain>
----------------------------->
250 ok
250 ok
<-----------------------------
<-----------------------------
DATA
----------------------------->
354 Enter mail
<-----------------------------
(E-mail body)... .
----------------------------->
(Virus scan)
DATA
----------------------------->
354 Enter mail
<-----------------------------
E-mail body
----------------------------->
250 ok
250 ok
<-----------------------------
<-----------------------------
QUIT
----------------------------->
QUIT
----------------------------->
221 smtpserver
221 smtpserver
<-----------------------------
<-----------------------------