Hello there,
First, sorry for this long post but i'm trying to summarise and give all
required details at the same time :-)
I'm working on the implementation of a solution where some files are going to be
exchanged through Suse Proxy Suite thanks to lftp ftp client.
lftp (2.4.9) and Suse proxy suite (1.9) have been compiled and are running under
AIX 4.3.2
The connection between lftp and suse proxy suite is a LAN connection.
The connection between the ftp proxy and remote ftp servers is internet based.
I've been using Suse ftp proxy for a few weeks now and i'm much more used to
lftp.
The problem that i'll describe in this mail was previously encountered with all
remote ftp servers we were connecting to.
Since we upgraded to latest version of Suse proxy (1.8 -> 1.9) this problem only
appears on connections were passive ftp mode is used between the proxy and the
remote server.
I have "the feeling" that all of this could be related to some buffering issue
but it could be not :-)
So here's the problem i'm facing without any real solution until now.
When i try to send a very small file (20 bytes or so) to a given remote ftp
server the data connection seems to stall once lftp has sent the file.
After a while lftp automatically restarts the connection, then it stalls again
and so on...
Here's a transcript of the session when this occurs :
lftp login@xx.xx.xx.xx@yy.yy.yy.yy:~> put test.txt
---> TYPE I
<--- 200 Type set to IMAGE.
---> PASV
<--- 227 Entering Passive Mode (yy,yy,yy,yy,9,16).
---- Connecting data socket to (yy.yy.yy.yy) port 2320
---> STOR test.txt
---- Closing data socket
`test.txt' at 22 (100%) [Waiting for transfer to complete]
And after a while lftp tries again the operation :
<--- 425 Can't open data connection.
---> QUIT
<--- 221 Goodbye.
---- Closing control socket
---- Connecting to yy.yy.yy.yy(yy.yy.yy.yy) port 2321
<--- 220 frorweb4 FTP server (Version 1.9 - 2002/05/02 15:14:55) ready.
---> USER login(a)xx.xx.xx.xx
<--- 331 Password required
---> PASS XXXX
<--- 230-user logged in
<--- 230-Welcome by a FTP Server
<--- 230 user logged in
---> TYPE I
<--- 200 Type set to IMAGE.
---> SIZE test.txt
<--- 550 file does not exist
---> PASV
copy: put rolled back to 0, seeking get accordingly
<--- 227 Entering Passive Mode (yy,yy,yy,yy,9,16).
---- Connecting data socket to (yy.yy.yy.yy) port 2320
---> STOR test.txt
---- Closing data socket
Interrupt
<--- 425 Can't open data connection.
lftp login@xx.xx.xx.xx@yy.yy.yy.yy:~>
Now some more facts :
- Sending that same file to the same remote server with the basic Debian woody
ftp client works fine (or another ftp client).
- Sending that same small file with lftp to a local server (no proxy) works ok.
- Sending a bigger file (several kb) to the same remote ftp server with lftp
works fine but it can sometimes fail with the same symptom.
- All connections between lftp and the proxy are established in passive mode and
on specific pair of ports (ctrl/data) due to firewall restrictions.
What i have tried to have it working :
- I've played with the MaxRevBufSize under Suse ftp proxy but with no results.
- I've also tried limitating the rate into lftp and it seemed to work when
lowering the rate to just a few bytes per second what is not really an
acceptable solution :-)
So basically the problem seems to be related to a combination of 3 or 4 factors
:
- a given remote ftp server (for instance it has occured with "G6 FTP Server
v2.0 (beta 4)" and "WS_FTP Server 3.0.1")
- the use of suse proxy suite
- the use of lftp
- sending a very small file
I hope that you'll apologize for this long post and even better, than someone
would have an idea of how to solve this problem :-)
Thanks in advance for having it a read.
Alex.
