Re: Re: Net::FTP via CGI mystery

[George_Sherston]

I tried increasing the debug level as you suggest, and it leaves me more baffled, but in a more specific way. First, I boiled down the script to the absolute minimum necessary to recreate the problem. It's now:

#!/usr/bin/perl -w

use strict;
use Net::FTP;
#use CGI::Carp qw(fatalsToBrowser warningsToBrowser);

my $ftp = Net::FTP->new("ftp.xxxxx.xxx");
$ftp->pasv;
$ftp->login('xxx','xxx');
my @files = $ftp->ls('/tst') or die "could not do ls";

print "Content-Type: text/html\n\n";
print "$_\n" for @files;
print "done\n";

Now, it still works fine when run from the command line, and fails when run from the browser. When it fails in the browser I just get an internal server error, because I deleted CGI::Carp, but reviewing the error logs shows the following (n.b. I tried this with a different ftp server too, so I really think that the problem is here):

Output from the script when run from the COMMAND LINE

Net::FTP: Net::FTP(2.61)
Net::FTP:   Exporter(5.562)
Net::FTP:   Net::Cmd(2.20)
Net::FTP:   IO::Socket::INET(1.25)
Net::FTP:     IO::Socket(1.26)
Net::FTP:       IO::Handle(1.21)

Net::FTP=GLOB(0x81177a8)<<< 220 xxxxxxxx.xxx ULTRA FTP SERVER
Net::FTP=GLOB(0x81177a8)>>> PASV
Net::FTP=GLOB(0x81177a8)<<< 530 Please login with USER and PASS.
Net::FTP=GLOB(0x81177a8)>>> user xxx
Net::FTP=GLOB(0x81177a8)<<< 331 Password required for xxx.
Net::FTP=GLOB(0x81177a8)>>> PASS ....
Net::FTP=GLOB(0x81177a8)<<< 230 CyBo welcomes replicant xxx.
Net::FTP=GLOB(0x81177a8)>>> PASV
Net::FTP=GLOB(0x81177a8)<<< 227 Entering Passive Mode (XXX,XX,XXX,XXX,
+XXX,XXX).
Net::FTP=GLOB(0x81177a8)>>> NLST /tst
Net::FTP=GLOB(0x81177a8)<<< 150 Opening ASCII mode data connection for
+ file list
Net::FTP=GLOB(0x81177a8)<<< 226 Transfer complete.
Content-Type: text/html

/tst/graphics
/tst/style
/tst/images
done
Net::FTP=GLOB(0x81177a8)>>> QUIT
Net::FTP=GLOB(0x81177a8)<<< 221 Goodbye.

Error Log report when run from the WEB BROWSER

Net::FTP: Net::FTP(2.61)
Net::FTP:   Exporter(5.562)
Net::FTP:   Net::Cmd(2.20)
Net::FTP:   IO::Socket::INET(1.25)
Net::FTP:     IO::Socket(1.26)
Net::FTP:       IO::Handle(1.21)

Net::FTP=GLOB(0x8286474)<<< 220 xxxxx.xxx ULTRA FTP SERVER
Net::FTP=GLOB(0x8286474)>>> PASV
Net::FTP=GLOB(0x8286474)<<< 530 Please login with USER and PASS.
Net::FTP=GLOB(0x8286474)>>> user xxx
Net::FTP=GLOB(0x8286474)<<< 331 Password required for xxx.  
Net::FTP=GLOB(0x8286474)>>> PASS ....
Net::FTP=GLOB(0x8286474)<<< 230 CyBo welcomes replicant xxx.
Net::FTP=GLOB(0x8286474)>>> PORT XXX,XX,XXX,XXX,XXX,XXX
Net::FTP=GLOB(0x8286474)<<< 200 PORT command successful.
Net::FTP=GLOB(0x8286474)>>> NLST /tst
Net::FTP=GLOB(0x8286474)<<< 425 Can't build data connection: Connectio
+n refused
could not do ls at ftp.pl line 9.
Net::FTP=GLOB(0x8286474)>>> QUIT
Net::FTP=GLOB(0x8286474)<<< 221 Goodbye.

So... it seems that what's happening is that when run from the browser the script doesn't go into passive mode (whatever that means)... but I thought it already was in passive mode. I'm completely out of my depth here, and I would be most grateful for a steer on how to get this to work.

§ George Sherston

[BrowserUk]

The following extract from the wsftp help might clarify things a little?

Passive Transfers (definition)

Normally, when you connect to an FTP site, the site establishes the da
+ta connection to your PC (the client). However, if the site allows pa
+ssive transfers, you can have your PC establish the data connection.
We recommend that you use passive mode for most transfers. Note that p
+assive mode may be required for users who are behind some types of ro
+uter-based firewalls or behind a gateway requiring passive transfers.

My only thought is that maybe one way is bypassing a proxy/firewall and the other isn't? HTH.

[George_Sherston]

I don't *think* that's the problem, because in both cases the attempt to access the remote ftp server is coming from the same place - namely my script. The only difference is in where I'm calling the script from, as far as I can see. Also, it logs in to the remote ftp server either way I call it. But it seems that, called from the browser, it doesn't send a PASV command to the ftp server. I'm not sure why, or why this is a bad thing. But what I really want to know is... how do I make it work??

§ George Sherston

[Fastolfe]

Call the 'pasv' method before you do your 'ls'.

What's likely happening is that Net::FTP is doing some configuration based on your user environment, and that environment differs from the environment present when Net::FTP is invoked from within a CGI script. You just don't know it. Be explicit and set 'pasv' if your network/firewall configuration requires that you use it.