Issue: Samba 2.0.7 and Windows 9X do not respond correctly to NetBIOS DGRAM

[Richard Sharpe]

Hi,

Here is an issue that I would like some comments on.

There are two, related issues, as I discovered after talking to a person
who is trying to use libsmbclient. They relate to the way that libsmbclient
browses workgroups. It does so by sending a GetBackupList request, and then
connecting to the IPC$ share on the first server returned and doing a
NetServerEnum request.

1. Samba 2.0.7 will not respond to a GetBackupList that is sent from the
same machine that Samba is running on (by a program linked against
libsmbclient). Samba 2.2.0 and Samba HEAD have been fixed to handle this
correctly.

This can be handled by documenting the need to upgrade to Samba 2.2.0, and
is perhaps not so likely to occur in the field.

There is a small patch that could be applied to Samba 2.0.7 that would fix
this problem, in any case.

2. A Windows 9X system that happens to be the local master browser for its
workgroup will not respond to GetBackupList requests sent by any
libsmbclient using program, since libsmbclient sends the UDP NetBIOS DGRAM
request from a port number larger than 1023 and to port 138. Windows 9X
requires that the request come from port 138 and go to port 138.

This can only be handled correctly by running a daemon as root that can
proxy port 138.

There are a couple of ways around this problem:

a. Require that nmbd run on the Linux machine and add code to nmbd that can
send the requests on behalf of the libsmbclient using program.  This would
be the answer if the user installs Samba on the machine.

b. Run a small daemon that handles GetBackupList and other requests on
behalf of all programs using libsmbclient. This would be the choice if the
user has not installed Samba.


Regards
-------
Richard Sharpe, sharpe at ns.aus.com
Samba (Team member, www.samba.org), Ethereal (Team member, www.ethereal.com)
Contributing author, SAMS Teach Yourself Samba in 24 Hours
Author, Special Edition, Using Samba