Christopher R. Hertel
crh at nts.umn.edu
Wed Jan 12 22:10:52 GMT 2000
> also see rfc 1088.txt... i think.
No, Luke. *FORGET* about 1088!
RFC1088: A Standard for the Transmission of IP Datagrams over NetBIOS
We do NetBIOS over IP, not IP over NetBIOS. I don't think that 1088 is
RFC 1001/1002 talk about the proper handling of group names in an NBT
environment using NBNS and the Datagram service. Microsoft decided to
implement it differently. There was a long discussion about this in
October on the CIFS list. (October, week 2 & 3.)
The NBNS (aka. WINS) server should keep track of *all* registered IPs for
a group name. When a query for that name is received, the NBNS server
sends back a datagram listing all of the IPs. If that UDP datagram is not
big enough to hold the entire list, then the truncation bit is set. If
the truncation bit is set, then the query is repeated over TCP so that the
whole list can be sent.
Further, if a client wishes to send a multicast message to all members of
a group, it can send the message to the Datagram service. This service
will use the NBNS list to repeat the message to all members of the group.
---- However, Microsoft did not implement this feature of the RFCs. ----
As you note, Microsoft short-cut the group names by registering the
broadcast address 255.255.255.255 for group names. This, of course, is
broken. It means that you can't multicast to members of a group if they
are not within your broadcast domain.
There is one exception, though. It's the "Internet Group". These are
type <1c> names. In this case, MS stores a maximum of 25 IPs. That's
the number that will fit into a UDP query response. They do not
implement the TCP option.
Paul Leach, when asked about this odd behavior, wrote "Further, I believe
1001/1002 in general to be overspecified."
> On Thu, 13 Jan 2000, Maxim Berlin wrote:
> > Hello Giulio,
> > Thursday, January 13, 2000, you wrote:
> > 
> > GO> wins hook fires for "WORKGROUP <00>" with ip 255.255.255.255.
> > GO> Is this correct being WORKGROUP <00> a group name?
> > GO> This cause the log file I use to register the name/ip mappings to
> > GO> include the mapping "WORKGROUP 255.255.255.255"
> > 
> > http://support.microsoft.com/support/kb/articles/Q163/4/09.asp?LNG=ENG&SA=ALLKB
> > ..
> > Group (G): A normal group; the single name may exist with many IP
> > addresses. WINS responds to a name query on a group name with the
> > limited broadcast address (255.255.255.255). Because routers block the
> > transmission of these addresses, the Internet Group was designed to
> > service communications between subnets.
> > ...
> > Best wishes,
> > Maxim mailto:mak at rtsnet.ru
> <a href="mailto:lkcl at samba.org" > Luke Kenneth Casson Leighton </a>
> <a href="http://www.cb1.com/~lkcl"> Samba and Network Development </a>
> <a href="http://samba.org" > Samba Web site </a>
> <a href="http://www.iss.net" > Internet Security Systems, Inc. </a>
> <a href="http://mcp.com" > Macmillan Technical Publishing </a>
> ISBN1578701503 DCE/RPC over SMB: Samba and Windows NT Domain Internals
-- I have a shoehorn, the kind with teeth. --
Christopher R. Hertel -)----- University of Minnesota
crh at nts.umn.edu Networking and Telecommunications Services
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