From: Gavin Kistner <gavin.kistner@...>
Date: 2006-10-19T03:19:56+09:00
Subject: Re: newbie ftp problem

From: lsumnler@gmail.com [mailto:lsumnler@gmail.com] 
> ftp = Net::FTP::new('my.url.com')
> ftp.login('login_id','login_pass',nil)
> ftp.chdir('data')
> 
> all goes fine but at this point I have tried all of the following and
> get the same errors
> 
> files = ftp.list('data')
> files = ftp.dir('data')
> files = ftp.dir(dir = nil)
> files = ftp.nlst('data')
> 
> Net::FTPPermError: 500 Invalid PORT command.

You changed directories into 'data', and are then trying to list a
'data' dir?

FWIW, all the above worked fine with me using Ruby 1.8.5 on Windows,
going to a known-working and accessible FTP server. Smells like either a
firewall/port-blocking issue, or a double-NAT issue. To be sure: can you
FTP from the command line/shell just fine?