metasploit-framework/lib/net/ssh/verifiers/lenient.rb

# -*- coding: binary -*-
require 'net/ssh/verifiers/strict'

module Net; module SSH; module Verifiers

  # Basically the same as the Strict verifier, but does not try to actually
  # verify a connection if the server is the localhost and the port is a
  # nonstandard port number. Those two conditions will typically mean the
  # connection is being tunnelled through a forwarded port, so the known-hosts
  # file will not be helpful (in general).
  class Lenient < Strict
    # Tries to determine if the connection is being tunnelled, and if so,
    # returns true. Otherwise, performs the standard strict verification.
    def verify(arguments)
      return true if tunnelled?(arguments)
      super
    end

    private

      # A connection is potentially being tunnelled if the port is not 22,
      # and the ip refers to the localhost.
      def tunnelled?(args)
        return false if args[:session].port == Net::SSH::Transport::Session::DEFAULT_PORT
        
        ip = args[:session].peer[:ip]
        return ip == "127.0.0.1" || ip == "::1"
      end
  end

end; end; end