&author.jerry;
&author.jelmer;
&author.dbannon;
&author.danshearer;
8 Apr 2003Analyzing and Solving Samba Problems
There are many sources of information available in the form
of mailing lists, RFCs and documentation. The documentation that comes
with the Samba distribution contains good explanations of
general SMB topics such as browsing.Diagnostics ToolsWith SMB networking, it is often not immediately clear what
the cause is of a certain problem. Samba itself provides rather
useful information, but in some cases you might have to fall back
to using a sniffer. A sniffer is a program that
listens on your LAN, analyzes the data sent on it and displays it
on the screen.Debugging with Samba Itself
One of the best diagnostic tools for debugging problems is Samba itself.
You can use the for both &smbd; and &nmbd; to specify the
debug level at which to run.
See the man pages for smbd, nmbd and
&smb.conf; for more information regarding debugging options. The debug
level can range from 1 (the default) to 10 (100 for debugging passwords).
Another helpful method of debugging is to compile Samba using the
gcc -g flag. This will include debug information in the binaries and
allow you to attach gdb to the running smbd/nmbd process.
To attach gdb to an smbd
process for an NT workstation, first get the workstation to make the
connection. Pressing ctrl-alt-delete and going down to the domain box
is sufficient (at least, the first time you join the domain) to
generate a LsaEnumTrustedDomains. Thereafter, the workstation
maintains an open connection and there will be an smbd
process running (assuming that you haven't set a really short smbd
idle timeout). So, in between pressing ctrl-alt-delete and actually
typing in your password, you can attach gdb and continue.
Some useful Samba commands worth investigating are:
&prompt;testparm | more
&prompt;smbclient -L //{netbios name of server}TcpdumpTcpdump was the first
UNIX sniffer with SMB support. It is a command-line utility and
now, its SMB support is somewhat lagging that of ethereal
and tethereal.
EtherealEthereal is a graphical
sniffer, available for both UNIX (Gtk) and Windows. Ethereal's
SMB support is quite good.For details on the use of ethereal, read the well-written
Ethereal User Guide.ethereal1Starting a capture.Listen for data on ports 137, 138, 139, and 445. For example, use
the filter port 137, port 138, port 139, or port
445 as seen in Starting a capture snapshot.A console version of ethereal is available as well and is called
tethereal.ethereal2Main ethereal data window.The Windows Network Monitor
For tracing things on Microsoft Windows NT, Network Monitor
(aka Netmon) is available on Microsoft Developer Network CDs,
the Windows NT Server install CD and the SMS CDs. The version of
Netmon that ships with SMS allows for dumping packets between any two
computers (i.e., placing the network interface in promiscuous mode).
The version on the NT Server install CD will only allow monitoring
of network traffic directed to the local NT box and broadcasts on the
local subnet. Be aware that Ethereal can read and write Netmon
formatted files.
Installing Network Monitor on an NT Workstation
Installing Netmon on an NT workstation requires a couple
of steps. The following are instructions for installing Netmon V4.00.349, which comes
with Microsoft Windows NT Server 4.0, on Microsoft Windows NT
Workstation 4.0. The process should be similar for other versions of
Windows NT version of Netmon. You will need both the Microsoft Windows
NT Server 4.0 Install CD and the Workstation 4.0 Install CD.
Initially you will need to install Network Monitor Tools and Agent
on the NT Server to do this:
Go to Start -> Settings -> Control Panel ->
Network -> Services -> Add.Select the Network Monitor Tools and Agent and click on OK.Click on OK on the Network Control Panel.Insert the Windows NT Server 4.0 install CD when prompted.
At this point, the Netmon files should exist in %SYSTEMROOT%\System32\netmon\*.*.
Two subdirectories exist as well, parsers\ which contains the necessary DLLs
for parsing the Netmon packet dump, and captures\.
To install the Netmon tools on an NT Workstation, you will first need to install the
Network Monitor Agent from the Workstation install CD.
Go to Start -> Settings -> Control Panel ->
Network -> Services -> Add.Select the Network Monitor Agent, click on OK.Click on OK in the Network Control Panel.
Insert the Windows NT Workstation 4.0 install CD when prompted.
Now copy the files from the NT Server in %SYSTEMROOT%\System32\netmon
to %SYSTEMROOT%\System32\netmon on the Workstation and set permissions
as you deem appropriate for your site. You will need administrative rights on the NT box to run Netmon.
Installing Network Monitor on Windows 9x/Me
To install Netmon on Windows 9x/Me, install the Network Monitor Agent
from the Windows 9x/Me CD (\admin\nettools\netmon).
There is a readme file located with the Netmon driver files on the CD if you need
information on how to do this. Copy the files from a working Netmon installation.
Useful URLsSee how Scott Merrill simulates a BDC behavior at
http://www.skippy.net/linux/smb-howto.html. FTP site for older SMB specs:
ftp://ftp.microsoft.com/developr/drg/CIFS/Getting Mailing List Help
There are a number of Samba-related mailing lists. Go to http://samba.org, click on your nearest mirror
and then click on Support and next click on
Samba-related mailing lists.
For questions relating to Samba TNG, go to
http://www.samba-tng.org/.
It has been requested that you do not post questions about Samba-TNG to the
main-stream Samba lists.
If you do post a message to one of the lists, please observe the following guidelines :
Always remember that the developers are volunteers, they are
not paid and they never guarantee to produce a particular feature at
a particular time. Any timelines are best guess and nothing more.
Always mention what version of Samba you are using and what
operating system it's running under. You should list the relevant sections of
your &smb.conf; file, at least the options in [global]
that affect PDC support.
In addition to the version, if you obtained Samba via
CVS, mention the date when you last checked it out. Try and make your questions clear and brief. Lots of long,
convoluted questions get deleted before they are completely read!
Do not post HTML encoded messages. Most people on mailing lists simply delete
them.
If you run one of those nifty I'm on holidays things when
you are away, make sure its configured to not answer mailing list traffic. Auto-responses
to mailing lists really irritate the thousands of people who end up having to deal
with such bad netiquet bahavior.
Don't cross post. Work out which is the best list to post to
and see what happens. Do not post to both samba-ntdom and samba-technical.
Many people active on the lists subscribe to more
than one list and get annoyed to see the same message two or more times.
Often someone will see a message and thinking it would be better dealt
with on another list, will forward it on for you.You might include partial
log files written at a debug level set to as much as 20.
Please do not send the entire log but just enough to give the context of the
error messages.If you have a complete Netmon trace (from the opening of
the pipe to the error), you can send the *.CAP file as well.
`
Please think carefully before attaching a document to an email.
Consider pasting the relevant parts into the body of the message. The Samba
mailing lists go to a huge number of people. Do they all need a copy of your
&smb.conf; in their attach directory?How to Get Off the Mailing ListsTo have your name removed from a Samba mailing list, go to the same
place where you went to
subscribe to it. Go to http://lists.samba.org,
click on your nearest mirror, click on Support and
then click on Samba related mailing lists.
Please do not post messages to the list asking to be removed. You will only
be referred to the above address (unless that process failed in some way).