Add -machine-only and -request-machine flags to GetUserSPNs.py

[ryanq47]

Add 2 flags to GetUserSPNs.py, which may be useful for machine account based cracking attempts (Pre2k, timeroasting, etc.)

-machine-only updates the LDAP filter to use objectCategory=computer instead of objectCategory=person

-request-machine functions the same as -request-user, but for machine accounts. It also auto-enables -request, and -machine-only

[alexisbalbachan]

The code looks really good, almost ready to merge! I just requested a couple of changes to:

1. Prevent users from using -request-user and -request-machine at the same time
2. Keep the code consistent (-request-user does not set the -request flag but -request-machine does, both implementations are fine by themselves but we should keep them aligned)

[alexisbalbachan]

Now that we have the flags to request a single user or a single machine we should not allow both of them at the same time. The suggestion below will create that restriction, otherwise it could be manually checked after parsing the arguments (if options.request_machine is not None and options.request_user is not None: .... error and exit here)

Suggested change

	parser.add_argument('-request-user', action='store', metavar='username', help='Requests TGS for the SPN associated '
	'to the user specified (just the username, no domain needed)')
	parser.add_argument('-request-machine', metavar='machinename', help='Requests TGS for the SPN associated to the machine specified. Example: `workstation01$`')
	exclusive_request_group = parser.add_mutually_exclusive_group()
	exclusive_request_group.add_argument('-request-user', action='store', metavar='username', help='Requests TGS for the SPN associated '
	'to the user specified (just the username, no domain needed)')
	exclusive_request_group.add_argument('-request-machine', metavar='machinename', help='Requests TGS for the SPN associated to the machine specified. Example: `workstation01$`')

[alexisbalbachan]

Just to make this consistent with request_user: Setting the flag options.request when requesting a machine is not necessary, just check for the flag in line 352 (by adding "or self.__requestMachine is not None"):

impacket/examples/GetUserSPNs.py

Line 352 in c1ccbbf

if self.__requestTGS is True or self.__requestUser is not None:

With that change, setting options.request is not needed anymore

Suggested change

	# auto enable machineonly, and request flag on -request-machine
	if options.request_machine is not None:
	options.machine_only = True
	options.request = True
	# auto enable machineonly, and request flag on -request-machine
	if options.request_machine is not None:
	options.machine_only = True