Revised 2017-08-31
Automation Tab
Drawing No. LP0997-C
Data Logger
Sixnet
®
Series SN/RAM
®
6000 & RAM 9000 Software Manual
- 183 -
FTP
:
When selected enter the FTP configuration data for delivery of the data log by FTP.
FTP Mode
Passive:
In passive mode FTP the client initiates both connections to the server, solving the
problem of firewalls filtering the incoming data port connection to the client from the server. When
opening an FTP connection, the client opens two random unprivileged ports locally (N > 1023 and
N+1). The first port contacts the server on port 21, but instead of then issuing a PORT command
and allowing the server to connect back to its data port, the client will issue the PASV command.
The result of this is that the server then opens a random unprivileged port (P > 1023) and sends P
back to the client in response to the PASV command. The client then initiates the connection from
port (N+1) to port P on the server to transfer data.
Active:
In active mode FTP the client connects from a random unprivileged port (N > 1023) to the
FTP server's command port, port 21. Then, the client starts listening to port (N+1) and sends the