title: Trying to download file from FTP results in an "500 Illegal PORT command" error
body: <p>If I execute this locally, everything works fine:</p>
  
  <pre><code>require 'net/ftp'
  
  ftp=Net::FTP.new("myftpserver.com", "username", "password")
  
  ftp.getbinaryfile("/myfile.zip","localfile.zip")
  ftp.close
  </code></pre>
  
  <p>If I attempt to execute it on the Linux server I am using, the result is:</p>
  
  <pre><code>/usr/local/lib/ruby/1.9.1/net/ftp.rb:273:in `getresp': 500 Illegal
  PORT command. (Net::FTPPermError)   from
  /usr/local/lib/ruby/1.9.1/net/ftp.rb:281:in `voidresp'  from
  /usr/local/lib/ruby/1.9.1/net/ftp.rb:304:in `block in voidcmd'  from
  /usr/local/lib/ruby/1.9.1/monitor.rb:201:in `mon_synchronize'   from
  /usr/local/lib/ruby/1.9.1/net/ftp.rb:302:in `voidcmd'   from
  /usr/local/lib/ruby/1.9.1/net/ftp.rb:317:in `sendport'  from
  /usr/local/lib/ruby/1.9.1/net/ftp.rb:325:in `makeport'  from
  /usr/local/lib/ruby/1.9.1/net/ftp.rb:358:in `transfercmd'   from
  /usr/local/lib/ruby/1.9.1/net/ftp.rb:420:in `block (2 levels) in
  retrbinary'   from /usr/local/lib/ruby/1.9.1/net/ftp.rb:166:in
  `with_binary'   from /usr/local/lib/ruby/1.9.1/net/ftp.rb:419:in `block
  in retrbinary'  from /usr/local/lib/ruby/1.9.1/monitor.rb:201:in
  `mon_synchronize'   from /usr/local/lib/ruby/1.9.1/net/ftp.rb:418:in
  `retrbinary'  from /usr/local/lib/ruby/1.9.1/net/ftp.rb:539:in
  `getbinaryfile'
  </code></pre>
  
  <p>What could be the problem?</p>