Cannot get binaryfile using Ruby from one FTP server under Amazon EC2 instance

Question

I have part of the code which is to get the binary file stream from one FTP server.

It works on my Ubuntu but the code cannot get the binary file from the FTP server when I tried it on the Amazon EC2 instance.

I tried to switch to another gem called open-uri. It can get the binary file stream on both my local PC and remote EC2 instance.

I use the default VPC of EC2 instance.

I already opened port 20 and 21 on EC2. I used dig ftp.cga.ct.gov and there is a answer on EC2.

If there is some point which is not clear for your guys, please point it out

Here is my code in the initialize method of one Ruby class:

def initialize(session_id)
  @session_id = session_id
  @count  = 1
  tries   = 10
  begin
      ftp = Net::FTP.new("ftp.cga.ct.gov")
      ftp.read_timeout = 500
      ftp.login
      ftp.chdir('/pub/data/')
      bill_str= ftp.getbinaryfile("bill_info.csv", nil)
      @bill_array = bill_str.delete("\"").split("\r\n")[1..-1]
  rescue Exception => e
      if (tries -= 1) > 0
        sleep 10
        print "re-connect"
        retry
      else
        print "Cannot open FTP\nThe error message is #{e}\n#{e.backtrace.join("\n")}"
     end
  else
    return true
  end
  super
end 

Answer 1

I think it is totally because of Amazon internal subnet bugs. Check my other question and the answer from myself.