Writing out a custom FTP scanner module

Let's try and build a simple module. We will write a simple FTP fingerprinting module and see how things work. Let's examine the code for the FTP module:

class MetasploitModule < Msf::Auxiliary 
  include Msf::Exploit::Remote::Ftp 
  include Msf::Auxiliary::Scanner 
  include Msf::Auxiliary::Report 
  def initialize 
    super( 
      'Name'        => 'FTP Version Scanner Customized Module', 
      'Description' => 'Detect FTP Version from the Target', 
      'Author'      => 'Nipun Jaswal', 
      'License'     =>  MSF_LICENSE 
    ) 
 
    register_options( 
      [ 
        Opt::RPORT(21), 
      ]) 
  end 

We start our code by defining the type of Metasploit module we are going to build. In this case, we are writing an auxiliary module that is very similar to the one we previously worked on. Next, we define the library files we need to include from the core library set, as follows:

We define the information of the module with attributes such as name, description, author name, and license in the initialize method. We also define what options are required for the module to work. For example, here, we assign RPORT to port 21, which is the default port for FTP. Let's continue with the remaining part of the module:

def run_host(target_host) 
     connect(true, false) 
    if(banner) 
    print_status("#{rhost} is running #{banner}") 
    report_service(:host => rhost, :port => rport, :name => "ftp", :info => banner) 
    end 
    disconnect 
  end 
end