WebOS 10.0 Application Guide
150 Chapter 6: Server Load Balancing 212777-A, February 2002
FTP Server Load Balancing
As defined in RFC 959, FTP uses two connections—one for control information and another for
data. Each connection is unique. Unless the client requests a change, the server always uses TCP
port 21 (a well-known port) for control information, and TCP port 20 as the default data port.
FTP uses TCP for transport. After the initial three-way handshake, a connection is established.
When the client requests any data information from the server, it will issue a PORT command
(such as ls, dir, get, put, mget and mput) via the control port.
There are two modes of FTP operation, active and passive:
nIn Active FTP, the FTP server initiates the data connection.
nIn Passive FTP, the FTP client initiates the data connection. Because the client also ini-
tiates the connection to the control channel, the passive FTP mode does not pose a prob-
lem with firewalls and is the most common mode of operation.

FTP Network Topology Restrictions

FTP network topology restrictions are listed below:
nFTP uses both a control channel and a data channel; both channels need to be bound to the
same real server.
nThe FTP server may initiate FTP data sessions.
nInformation exchanged on the control channel is used to determine the IP address and port
for data connections between the FTP server and the FTP client.

Configuring FTP Server Load Balancing

1. Make sure that a proxy IP address is enabled on the client port(s) or DAM is enabled.
2. Make sure the virtual port for FTP is set up for the virtual server.
3. Enable FTP parsing.
4. To make your configuration changes active, enter apply at any prompt in the CLI.
NOTE – You must apply any changes in order for them to take effect, and you must save
them if you wish them to remain in effect after switch reboot.
>> # /cfg/slb/virt <virtual server number>
>> Virtual Server 1# service ftp
>> Virtual Server 1 ftp Service# ftpp ena
>> Virtual Server 1 ftp Service# apply