Re: [Duplicity-talk] connect failed: Invalid argument.

[Tim Riemenschneider]

address@hidden schrieb:
> Hello,
>
> I am getting the following error:
>
> address@hidden duplicity-0.5.17]$ FTP_PASSWORD=xxxxxx /usr/bin/duplicity 
> /usr/local/  ftp://address@hidden:2121/backup/
> NcFTP version is 3.2.2
> connect failed: Invalid argument.
> connect failed: Invalid argument.
> connect failed: Invalid argument.
> Running 'ncftpls -f /tmp/duplicity-QkE_hG-tempdir/mkstemp-dbsEHg-1 -F -t 30 
> -o useCLNT=0,useHELP_SITE=0  -P '2121' -l 'ftp://localhost:2121/backup/'' 
> failed (attempt #1)
>
> It would be great if someone could shine some light on the "Invalid argument" 
> error.
>
> A little more about my setup. I am using a ssh tunnel to get to the main host 
> of my webserver and from there I go to the ftp server. Manually everything 
> works, i.e. I can login to the server via the tunnel. Also, if I supply the 
> wrong password to dulicity I get a wrong password error - so the connection 
> is working. 
>
> Thank you very much for your help.
> Best wishes,
> Phil
>
>   
I don't think that that can work. FTP uses two different streams: the
control-stream for the commands and the data for, well, the data.
When you tunnel port 21, you only tunnel the control-stream, not the
data-stream.
Sometimes this does work, but often it doesn't.
Specifically:
When the server is only available to some hosts, not the whole internet
(this is your case, i assume): the control-stream is tunneled from your
server-to-be-backuped to your webhost and from there to the ftpserver.
That means for the ftpserver the connection seemingly comes from your
webhost and is allowed. However when a data-stream is required, your
server tries to reach the ftpserver directly, which is probably not allowed.
But even when the ftpserver is available from everywhere, most
ftpservers check the source-address of the data-stream and discard
packages not coming from the connected host.

cu
Tim