Other FTP Proxy Issues

The FTP proxy does not permit the PASV command (used for third-party transfers).

The FTP proxy has a 10-minute time-out on the control connection for user requests. The responses from the backend server have only two minutes to arrive before timing out.

The maximum number of concurrent sessions available in the FTP proxy daemon is configurable through the variable N_Sessions. It contains the following items:

• sys=Screen (optional)

• prg=ftpp

• name=N_Sessions

• values=max # of sessions

• description="descriptive text" (optional)

• enabled | disabled (The default is enabled)

As initially installed, a global version of this variable is created that restricts the number of concurrent sessions to 100.

The following is an example of what you would type to display this (initial) variable while logged into the primary Screen:

admin% ssadm -r primary edit Initial
edit> vars print prg=ftpp name=N_Sessions
PRG="ftpp" NAME="N_Sessions" ENABLED VALUE="100" 
DESCRIPTION="limit # of concurrent sessions, FTP proxy" 

You can alter this number of sessions, perhaps to be more restrictive, on a particular Screen.

The following is an example of what you would type to do this while logged into the primary Screen:

edit> vars add sys=Screen prg=httpp name=N_Sessions value=66 
description="limit # of concurrent sessions on the Screen FTP proxy"
edit> quit

By configuring the FTP proxy on a Screen, the actual FTP service into that system becomes unavailable. To avoid confusion, define the destination address of proxy rules to exclude all the addresses of Screens. (You can still FTP out of the Screen, as necessary.)