For file transfer protocol (FTP) communication, clients open a TCP-based control channel on port 21. For active FTP, a second data channel is initiated from the server to the client through port 21. Avi Load Balancer only supports passive FTP, in which the client initiates the data channel through a high port negotiated with the server.

Passive FTP

Avi Load Balancer supports passive FTP using the following configuration:

A Note on High Availability

Exactly one SE in an SE group may deliver the FTP service at any given time. Virtual service scale-out to two or more SEs is not supported with Avi Load Balancer FTP. Therefore, legacy active/standby and 1+M elastic HA are supported. Active/active elastic HA is not.

The virtual settings configuration is as follows:

Application Profile

L4

TCP/UDP Profile

TCP Proxy

Service Ports

Set to Advanced through the Avi Load Balancer UI

Port

21

Virtual Service Settings:

Application Profile: L4

TCP/UDP Profile: TCP-proxy

Service Ports: Set to Advanced through the Avi Load Balancer UI

Port: 21

Port: 1024-65534

Pool Settings:

Load Balance Algorithm: Least Connections

Persistence: Client IP

Health Monitor: TCP

Health Monitor Port: 21

Port Translation: Deactivated

Active FTP

Active FTP is not supported. Avi Load Balancer recommends the use of passive FTP as a workaround.

> ftp  ftp.test.com
Connected to ftp.test.com.
ftp.test.com FTP server ready.
Name (test:user): anonymous
Password required for anonymous.
Password: ******
User anonymous logged in.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> passive
Passive mode on.