I stripped out the address and found domains(x's y's) because they are irrelevant to the error.
Code:
root@bt:/pentest/python/impacket-examples# python samrdump.py 192.168.x.x
Retrieving endpoint list from 192.168.x.x
Trying protocol 445/SMB...
Found domain(s):
. xxxxxx
. yyyyyy
Looking up users in domain xxxxx
Protocol failed:
Traceback (most recent call last):
File "samrdump.py", line 182, in <module>
dumper.dump(address)
File "samrdump.py", line 66, in dump
entries = self.__fetchList(rpctransport)
File "samrdump.py", line 142, in __fetchList
resp = rpcsamr.enumusers(domain_context_handle)
File "/usr/lib/pymodules/python2.6/impacket/dcerpc/samr.py", line 697, in enumusers
retVal = SAMRRespEnumDomainUsersHeader(data)
File "/usr/lib/pymodules/python2.6/impacket/dcerpc/samr.py", line 472, in __init__
if aBuffer: self.load_header(aBuffer)
File "/usr/lib/pymodules/python2.6/impacket/ImpactPacket.py", line 256, in load_header
hdr_len = self.get_header_size()
File "/usr/lib/pymodules/python2.6/impacket/dcerpc/samr.py", line 498, in get_header_size
assert var_size > 0
AssertionError