ftp Issue

[El Marko]

Our business runs an ftp site whereby employees and clients can exchange
larger sized files.

Over the past months, an increasing number of clients are unable to connect
and the only common thread is that they are using XP Pro.

Our regular ftp port is open on the firewall, but is there another port we
may be blocking that is hindering data that XP needs for ftp connections?

mm

 

[Tim Slattery]

Our business runs an ftp site whereby employees and clients can exchange
larger sized files.

Over the past months, an increasing number of clients are unable to connect
and the only common thread is that they are using XP Pro.

Our regular ftp port is open on the firewall, but is there another port we
may be blocking that is hindering data that XP needs for ftp connections?

FTP uses port 21 for its command streams, but it opens another port to
actually exchange data. If something about your networking setup is
preventing other ports from opening, then that can kill an FTP
session.

In particular, using a NAT router will kill normal FTP sessions. To
get around that you have to tell your client to use passive mode. XP's
builtin command-line FTP client can't do that, but nearly any GUI
client can.

 

[David H. Lipman]

From: "Tim Slattery" <[email protected]>

|
| FTP uses port 21 for its command streams, but it opens another port to
| actually exchange data. If something about your networking setup is
| preventing other ports from opening, then that can kill an FTP
| session.
|
| In particular, using a NAT router will kill normal FTP sessions. To
| get around that you have to tell your client to use passive mode. XP's
| builtin command-line FTP client can't do that, but nearly any GUI
| client can.
|

It doesn't have to be a GUI. For example the GNU WGET.EXE utility has the --passive-ftp
switch parameter.

The TCP ports are 20 and 21.

However, since this is a WinXP problem I think it is the WinXP FireWall that is at fault.
Either it is blocking the ports, the application or both.

 

[Charlie Tame]

If your FTP server has only the regular port it will not be able to accept
connections from a "Passive" mode client. Passive is good fro clients bad
for servers, Active is more secure for servers but bad for clients with
firewalls or some modem / routers.

http://www.slacksite.com/ftp.html

Most likely I think is that their IE has been set to passive (Tools>internet
options>advanced>use passive mode etc) and your server is trying to use
ports blocked by your firewall. I think any of the replies could be correct
so by all means investigate all of them.

Charlie