如果我在本地执行,一切正常：
require 'net/ftp'
ftp=Net::FTP.new("myftpserver.com","username","password")
ftp.getbinaryfile("/myfile.zip","localfile.zip")
ftp.close
如果我尝试在我正在使用的Linux服务器上执行它,结果是：
/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'
可能是什么问题呢？
解决方法
我在
http://www.ruby-forum.com/topic/161274发现了答案：
Beyond firewalls,active ftp won’t work behind a NAT device. Ftp
servers sometimes say illegal port command if you tell them that your
address is a private ip address like 192.168.x (your address on the
network behind the nat device)
添加：
ftp.passive = true
修复.