gistfile1.rb

#!/usr/bin/env ruby

require 'rubygems'
require 'active_ldap'

ActiveLdap::Base.setup_connection(
  :host => 'ldap.example.com',
  :base => 'dc=example,dc=com',
)

class User < ActiveLdap::Base
  ldap_maping

  class << self
    def authenticate(dn, password)
      user = find(dn)
      user.bind(password)
      user
    rescue ActiveLdap::EntryNotFound,
           ActiveLdap::AuthenticationError,
           ActiveLdap::LdapError::UnwillingToPerform
      nil
    end
  end
end

if $0 == __FILE__
  p User.authenticate('foo', 'bar')
end