root@kali:~# enum4linux -a -o www.harvard.edu
Starting enum4linux v0.8.9 ( http://labs.portcullis.co.uk/application/enum4linux/ ) on Mon Oct 24 00:37:22 2016
==========================
| Target Information |
==========================
Target ........... www.harvard.edu
RID Range ........ 500-550,1000-1050
Username ......... ''
Password ......... ''
Known Usernames .. administrator, guest, krbtgt, domain admins, root, bin, none
=======================================================
| Enumerating Workgroup/Domain on www.harvard.edu |
=======================================================
[E] Can't find workgroup/domain
===============================================
| Nbtstat Information for www.harvard.edu |
===============================================
Looking up status of 104.16.155.6
No reply from 104.16.155.6
========================================
| Session Check on www.harvard.edu |
========================================
Use of uninitialized value $global_workgroup in concatenation (.) or string at ./enum4linux.pl line 437.
[E] Server doesn't allow session using username '', password ''. Aborting remainder of tests.