Use the EPSV4 statement to direct the FTP client to use EPSV and EPRT commands on IPv4 sessions. The locsite subcommand is also available to set this parameter.
Syntax
.-EPSV4 FALSE------. >>-+------------------+---------------------------------------->< '-EPSV4--+-FALSE-+-' '-TRUE--'
Parameters
- FALSE
- Prevents the client from using EPRT and EPSV commands on IPv4 sessions. This is the default.
- TRUE
- Directs the client to use EPRT and EPSV commands on IPv4 sessions.
Usage notes
EPRT and EPSV commands are described in RFC 2428. If the server rejects an EPRT or EPSV command during the session, the client stops sending EPRT and EPSV to that server regardless of how you have set EPSV4.
Guideline: If your client has trouble establishing a data connection on an IPv4 security protected, encrypted session through an NAT firewall, coding EPSV4 TRUE in the client's FTP.DATA can help.
Restrictions:
- The FTP server ignores this statement.
- Socksified sessions use PASV or PORT commands to establish data connections, as specified by the FWFRIENDLY setting. When EPSV4 is TRUE, the client attempts EPSV but never EPRT to establish a socksified data connection.
- Some FTP servers support EPRT and EPSV commands, but do not reply as described in RFC 2428. If the FTP server reply to EPSV or EPRT does not conform to RFC 2428, the client reacts as if the server has rejected the command.
- RFC 2428 stipulates EPSV is the preferred command to establish data connections. Therefore, when EPSV4 is TRUE, the client tries EPSV regardless of how you have set FWFRIENDLY. The client uses EPRT only to set up a data connection for proxy transfer.
Examples
To direct the client to use EPSV
and EPRT commands on IPv4 FTP sessions, use the following code:
EPSV4 TRUE