To monitor FTP
services, the NetScaler appliance opens two connections to the FTP server. It
first connects to the control port, which is used to transfer commands between
a client and an FTP server. After it receives the expected response, it
connects to the data port, which is used to transfer files between a client and
an FTP server. Only when the FTP server responds as expected on both
connections is it marked UP.
Note: Monitor probes originate from the NetScaler IP (NSIP) address.
The NetScaler appliance has two built-in monitors for FTP services: the FTP monitor and the FTP-EXTENDED monitor. The FTP-EXTENDED monitor is a scriptable monitor. It uses the nsftp.pl script. The FTP-EXTENDED monitor script is enhanced to send secure probes to FTP services. You can create a monitor of type USER and specify this script name, or you can create a monitor of type FTP-EXTENDED. In the latter case, the nsftp.pl script is automatically taken from the default directory.
To send secure FTP probes to FTP services by using the NetScaler command line
At the command prompt, type:
add lb monitor <monitorName> <type> -scriptName <string> -scriptArgs <string> -secure ( YES | NO )
To send secure FTP probes to FTP services by using the NetScaler GUI
1. Navigate to Traffic Management > Load Balancing > Monitors and, for Type, specify USER or FTP-EXTENDED.
2. Depending on which type you specified, set one of the following groups of parameters:
a. USER: In Special Parameters, specify a Script Name (nsftp.pl) and the Script Arguments.
b. FTP-EXTENDED: In Special Parameters, specify a File Name, User Name, and Password.
To configure built-in monitors to check the state of FTP services, see Configuring Monitors in a Load Balancing Setup.