Re: ftp client autoconnect

Giganews Newsgroups
Subject: Re: ftp client autoconnect
Posted by:  J. Peter Mugaas (oma002…@mail.wvnet.edu)
Date: Fri, 27 Jun 2003

In article <EF3D3594ED74E240al.barnett@nospam.data-freeway.co.uk>,
al.barnett@nospam.data-freeway.co.uk says...
> I am using D7 and the latest version of Indy V9.0.14.
>
> I have been trying to connect to a device that we develop in-house
> which implements an ftp server and upload various config files.
>
> I was implementing the Connect() causing an auto-login to occur
> but this was causing the ftp connection to be imediately terminated.
>
> Investigation found that auto-login was causing the SYST command to be
> sent to the server and our server was returning 502 - command not
> implemented.
> Unfortunately the ftp component only accepts 200, 215, 500 as valid
> responses
> and terminates the connection when it recieves a 502.
>
> I can get round the problem by not using the auto-login and doing it
> manually
> Connect(False);
> Login;
> Everything now works.
>
> My question is who is right?
> Should we be sending a different command response
> or should you be accepting more generic responses for this command.
>
I'm not completely sure but when looking at RFC 959, I found that the
502 means "Command not implemented".  The SYST command is used to get an
indentifier from the FTP server indicating the type of platform it's
running on (or says it's running on).  Many servers including some Win32
servers will indicate "Unix".

The SYST command is used by some clients for fingerprinting a server so
they can possibly make adjustments for uploading files with filenames
which are valid in the OS (MVS, IBM VM/CMS, and a few other systems have
their rules in that regard) and it used by some clients to know what
directory format to expect (I think TurboPower IPros does this).

The point I'm trying to make is that by not supporting the SYST command,
that server is probably going to create some unantipated problems and
the issue should be reported to that vendor.

Other than that, I don't see any particular reason why we shouldn't try
to continue the sesssion even if the SYST command doesn't work (this may
not be a bad idea anyway because there may be a few servers that have
disabled for security reasons - not a wise choice, IMAO).

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J. Peter Mugaas    E-Mail:  oma002…@mail.wvnet.edu
http://wvnvm.wvnet.edu/~oma00215/  ICQ Number:  14297043
Finger for PGP Key

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In response to

ftp client autoconnect posted by AToZedIndy on Fri, 27 Jun 2003