On 2/9/11 4:37:17 PM, Daniel Stenberg wrote:
On Wed, 9 Feb 2011, Leo wrote:
STAT /
...
But still I'm curious if those Cyberduck logs help understand how it
connects to both sites seemingly automatically?
It works without doing PASV or EPSV when doing directory listings by
the STAT command as shown up here. STAT sends contents over the
control connection instead of over a separate data connection (a
method that libcurl doesn't yet support).
If you do a file transfer instead of a directory listing it might act
differently.
Ha! You're right.
I never actually tried to transfer anything, just listed directory,
thinking the result must be the same.
So when I tried to transfer a file, Cyberduck could NOT send it to the
EPSV-liking site (even after listing directory). I had to switch
connection mode from Default to Active to enable transfer.
But anyway, it looks like I got there!
After Cyberduck, I checked Transmit - and it could list and transfer
files everywhere without changing anything.
I looked at the transcript, and noticed this everywhere:
200: PORT command successful. <Consider using PASV.>
which seemed to confirm Michael's suggestion that active mode
(--ftp-port) is universally used... But why it didn't work for me with
certain servers when using curl?
But then I recalled a little detail I forgot - and a little mix-up of
terminology doesn't make it easier :) - that --ftp-port doesn't imply
the PORT command, because the default is EPRT and you need to disable it
to use PORT.
So I added --disable-eprt and it seems to work with any server.
So the answer is active mode with the PORT command, just as Michael
suggested (+ EPRT suppressed)...
That is unless we have to deal with an issue that Michael mentioned (and
I did some more research to understand it better):
If multiple clients are involved, then the firewall
on the client becomes more important when using --ftp-port, because
the server will have to make a connection back to the client and the
client's firewall might not allow the incoming connection from the
server.
So I activated firewall on my Mac, and naturally neither Transmit nor my
program couldn't connect anywhere, with Transmit giving a proper warning:
"Error accepting data connection. This could be a problem with firewall
or proxy configuration. Try passive mode."
Transmit also has a preference to use Passive (PASV) mode.
Choosing PASV allowed most connections, but it still could NOT connect
to the EPSV-liking site (as expected).
Bottom line: there's nothing "magic" about those FTP clients, they work
exactly the same way as curl, just set initially to different
defaults... which is something you told me from the beginning. :)
Now I just need to pick my preferred default settings and let users
change them if required.
Anyway, the picture is now clear - thanks a lot Daniel and Michael for
all the great help with the issue! I can deal with the connection modes
on a conscious level now. :)
Best,
Leo
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