SMB directly hosted on TCP

Ville Herva vherva at
Mon Nov 13 14:45:34 GMT 2000

(My apologies if this has already been brought up -- I did try to search
the archive.)

"Windows 2000 supports file and printer sharing traffic by using the
Server Message Block (SMB) protocol directly hosted on TCP. This differs
from earlier operating systems, in which SMB traffic requires the NetBIOS
over TCP (NBT) protocol to work on a TCP/IP transport. Removing the
NetBIOS transport has several advantages, including:

      o  Simplifying the transport of SMB traffic.

      o  Removing WINS and NetBIOS broadcast as a means of name

      o  Standardizing name resolution on DNS for file and printer

If both the direct hosted and NBT interfaces are enabled, both methods are
tried at the same time and the first to respond is used. This allows
Windows 2000 to function properly with operating systems that do not
support direct hosting of SMB traffic. "


"NetBIOS over TCP traditionally uses the following ports: 

      nbname            137/UDP
      nbname            137/TCP
      nbdatagram        138/UDP
      nbsession         139/TCP 

Direct hosted "NetBIOS-less" SMB traffic uses port 445 (TCP and UDP). In
this situation, a four-byte header precedes the SMB traffic. The first
byte of this header is always 0x00, and the next three bytes are the
length of the remaining data. You can use the following steps to disable
NetBIOS over TCP/IP, forcing all SMB traffic to be direct hosted. "

This actually sounds quite good. It could in fact reduce overhead and
improve performance. What do you think?

Would it make sense/be feasible to support this on Samba?

(I'm not subscribed, so I'd appreciate CC'ing me -- I will, however, read
the archive.)

-- v --

v at

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