Problem with ftp

[baux]

excuse me for my english, i hope you understand me:

i've installed autapf in pc under a firewal and i've config autapf for rediredt all the request to port 21 in an other machine (AS400) evry port 21.
the connection make right, insert user and pasw ok. but when try to have a dir or put a file, after few minute show the message:

425 Not able to open data connection.

I don't understand..... where is the poblem?!?!

tnx for any reply

Ciao
CAMPIONI DEL MONDO!!!!!

[Johannes]

Hmm,

if you mean that the client and server can establish a connection then everything is probably configured correctly,

it might be just that ftp doesnt like going through a node, without knowing that its really there. Im not a pro at ftp, but maybe you can set the client in passive mode? (so that both sides know that thers something inbetween)

Also try playing around with the settings for ftp on client and server, and play with the firewall on all three machines, sometimes it can get complicated....

/Johannes

edit:typo

[NetworkActiv]

File Transfer Protocol (FTP) uses one base connection for authentication and control, and one additional connection for each transfer that takes place. A transfer can be of a file, a directory (folder) listing, or perhaps something else.


An example of an FTP session:

1. The session is established on the main port (such as port 21). This is done by the client connecting to the server's main FTP port number.

2. The client wishes to obtain a folder listing and so informs the server on the control connection.

3.
(when in passive mode): The server tells the client to connect to it on a pretty much randomly chosen port number to establish the transfer connection.
(when in normal mode): The client tells the server to connect to it on a pretty much randomly chosen port number to establish the transfer connection.

Because FTP uses these pretty much randomly chosen port numbers, one for each transfer, it is unable to be forwarded through a standard port forwarder.

(Note that in some instances, the FTP connection stuff is actually more complex than what is described herein)


Q: Why does FTP use multiple port numbers and connections for just one client session?

A: Because FTP is a very old protocol that was devised before TCP/IP supported having multiple simultaneous connections to the same port number on the same IP address.

Newer protocols, such as SFTP (over SSH) or HTTP are preferred over FTP as they use only one port number for all transfers and connections. NetworkActiv Software provides a free HTTP server, NetworkActiv Web Server.

[baux]

[NetworkActiv]

If you feel competent in working with ports, the netstat command (or with a packet capturing tool), and advanced settings to do with your FTP software (if such settings exist), it would probably be possible to get a given FTP connection through AUTAPF to work, but I can not dedicate the time to help you get that working. That could be difficult, and may not be possible depending on your FTP client software and depending on what modes are supported by the FTP server.

I'm too busy at this time to implement a feature in AUTAPF that would make it automatically support FTP