The passive command enables or disables PASSIVE mode. PASSIVE mode has now become the default setting in many implementations and is used to reach the internet from a local network via a firewall. Such firewalls often suppress active connection setup into the network protected by the firewall.
Details on PASSIVE mode are provided in the “interNetServices Administrator Guide”.
passive |
[ on | off ] |
on
PASSIVE mode is enabled.
If no operand is specified, this corresponds to the specification passive on.
off
PASSIVE mode is disabled.
off is the default if no passive statement is specified.
In PASSIVE mode all subsequent file transfer commands are handled with active client and passive child, in other words by means of PASV and EPSV commands. This applies until a negative acknowledgment is received by the server for a PASV or EPSV command, for example when a connection to the server has been terminated.
The following applies for the EPSV command on the child side: If you specify the ALL parameter in the EPSV command, all subsequent PORT and EPRT commands are rejected with “522 PORT command not successful” or “522 EPRT command not successful”.
The status command allows you to check whether PASSIVE mode is set:
ftp> status Connected to PGAB0021, port 21. No proxy connection. Passive Mode: on ...
Each time you enter the passive command the latest setting is output.