F-Secure Internet Gatekeeper for Linux/Administrator’s Guide
140
11.5
FTP Proxy Process
The FTP service relays both the control session and data session. This section describes how
common protocols are processed with the FTP proxy.
Proxy mode, Passive FTP
Client Internet
Gatekeeper
(fsigk, 0.0.0.1)
FTP server
(ftpserver, 0.0.0.2)
TCP connect(to:
0.0.0.1:9021)
----------------------------->
220 fsigk at fsigk
<-----------------------------
USER user@ftpserver
----------------------------->
TCP connect(to:
0.0.0.2:21)
----------------------------->
220 ftpserver
<-----------------------------
USER user
----------------------------->
331 Password required
331 Password required
<-----------------------------
<-----------------------------
PASS password
----------------------------->
PASS password
----------------------------->
230 User logged in.
230 User logged in.
<-----------------------------
<-----------------------------
PASV
----------------------------->
PASV
----------------------------->
227 Entering Passive Mode (0,0,0,2,0,2)
<-----------------------------
227 Entering Passive Mode (0,0,0,1,0,1)
<-----------------------------
RETR /file
----------------------------->
RETR /file
----------------------------->
TCP connect(To: 0.0.0.1:1)
=====================>
TCP connect(To:
0.0.0.2:2)
=====================>
150 Opening data connection.
<-----------------------------
150 Opening data connection.
<-----------------------------
File information
<=====================
(Virus scan)
File information
<======================
TCP close
TCP close.
<=====================
<=====================
226 Transfer complete.
226 Transfer complete.
<-----------------------------
<-----------------------------
QUIT
----------------------------->
QUIT
----------------------------->
221 Goodbye.